This eighth-grade science lesson is about sunspots and pulleys. The portion of the lesson on pulleys constitutes the ninth lesson in a sequence of 12 lessons on machines. The lesson is 51 minutes in duration. There are 33 students in the class.

00:00:10Okay, do I have any others of these pages?
00:00:14Going once.
00:00:15Oh, I do.
00:00:16Yeah. That's it. That's really great.
00:00:17[ bell ]
00:00:18Thank you. Can I have any others?
00:00:23Miguel, sit down.
00:00:25Audrey. Audrey, put them away.
00:00:27What is this?
00:00:30It's my (inaudible).
00:00:33It's what?
00:00:35He's recording.
00:00:36Thank you.
00:00:37Oh, wait- I need to write my name on it.
00:00:40Is my name on it?
00:00:41I didn't-
00:00:42It's fine. I put your name on it.
00:00:45Oh. Sorry.
00:00:46Guys, get out your binder reminders.
00:00:49Oh. I didn't do it.
00:00:50Write down tonight's homework assignment.
00:00:51Are we going outside and do sunspots?
00:00:53Yeah. That's the plan. Audrey, sit down.
00:00:55(inaudible) go to the office and get my-
00:00:58Get what?
00:00:59My binder reminder.
00:01:00Why? What did you leave it up there for?
00:01:03Because I just left it up there.
00:01:05Where is it? I'll send Justin for it.
00:01:08It's up there.
00:01:14(inaudible) gardener. I have to go get it.
00:01:16Okay. There you go. Justin will get it for you. You need to sit down.
00:01:24Her binder reminder.
00:02:06What did I do? Oh, //my gosh.
00:02:10//You were late. You were late.
00:02:13I was not late.
00:02:17You need to write down tonight's homework assignment. It says read pages 145 to 149.
00:02:23On page 149, I'd like you to do questions one through four, please.
00:02:27Number 18?
00:02:28Questions one through four. Number 18. And as always write out the questions and the answers. What do you need, Miguel?
00:02:40Cindy, could you go sit in your actual seat? Thank you. Yes, Audrey?
00:02:50Yes, Audrey.
00:02:52Oh. I hate when you guys do that.
00:02:56As soon as you've got that written down, we need our little sunspot data sheets,
00:03:01but I can't remember whether we had some for today or whether we need to make some.
00:03:06We need to make some.
00:03:07We need to make some.
00:03:08Okay. Then I'm gonna pass out a piece of paper to you.
00:03:10Tear it in half like we've done before, take about an inch off the bottom,
00:03:13and I'll pass out compasses so that we can get the sun's shape drawn before we head outside.
00:03:23(Punch and munch) tomorrow.
00:03:33I think I left enough for Matt so-
00:03:44Cindy, can you wash that off your hand, please. There's a sink right behind you.
00:03:48Did you go find Audrey's stuff yet? After you take roll.
00:03:52Okay, that's cool.
00:03:53We need another one for Matt.
00:03:54Okay. I thought I gave you one, but-
00:03:55(inaudible) one for Matt.
00:04:04There's one. Pass that one back to Matt, would you?
00:04:06Mr. Melville, are you gonna watch this tape after?
00:04:10Okay. Good.
00:04:11I'll have no idea. Why? Are you planning on doing some rude symbol while my back is turned?
00:04:18Is that it?
00:04:19No. Because like if we do something then you're gonna see it then we're gonna get caught and get in trouble anyway.
00:04:21I see.
00:04:22I was just asking.
00:04:24No. I will never see it.
00:04:28You're funny.
00:04:37Take two, pass it back. And there's one extra for Matt.
00:04:41Cindy, once it's washed off, you can sit down.
00:04:45I need a towel.
00:04:46I see. There's some next to the sink over there.
00:04:51Take two, and pass the rest back.
00:04:54Set the compass at four and a half centimeters, please.
00:04:58Audrey, put that away or I'm gonna read it out loud to everybody.
00:05:01Okay, okay, okay, okay, okay, okay, okay.
00:05:03On tape.
00:05:04Read it out loud.
00:05:05Thank you.
00:05:06That'll be the most funniest moment.
00:05:08That would make my day.
00:05:11Then we can catch her reaction on tape, too. That'd be really great.
00:05:17Miguel, it's just a compass.
00:05:19Separate them in two halves, take about an inch off the bottom, please.
00:05:22I'll be there anyway.
00:05:23Draw your sun circle about in the center.
00:05:26I'm just kidding.
00:05:27Esther, how much is like Alfred's?
00:05:32Fold it in half, turn.
00:05:34That's all you had to do?
00:05:36Yeah. That's it. That's it.
00:05:41Where's Randy?
00:05:43He went to the nurse's office.
00:05:45I forgot.
00:05:46He wasn't feeling well.
00:05:47Excuse me.
00:05:56Leave him alone, Audrey. Just a little.
00:06:04Mr. Melville?
00:06:06(inaudible) Jack's name?
00:06:08Uh, you can actually draw a line through Jack's name on there and, uh- was that it for this class that transferred to the high school?
00:06:16Was it just Jack? I think it was just Jack actually so that would be fine.
00:06:36Which one is number one, Justin? Which one of those is number one?
00:06:41I got number two.
00:06:42Okay, thanks.
00:07:00(inaudible) put it on- how many centimeters?
00:07:02Four //and a half.
00:07:03//Four and a half centimeters.
00:07:07That ain't gonna be (inaudible).
00:07:08How do you know?
00:07:12Carly, the camera loves you.
00:07:18Can we do the other circle for the other paper too, Mr. Melville?
00:07:21Uh, yes. Please do both circles because I don't want to have to do this again tomorrow. I'd just like to go out and get the sunspots real quick.
00:07:29Mr. Melville, do you want us to act like perfect kids right about now?
00:07:32You know what? Every single day I would like you to act like perfect kids. If-
00:07:36Well, I'm just saying-
00:07:37If today is the best you can do for being perfect, //I'll take it.
00:07:39//(Keep it on me).
00:07:40That would be great. Yes, thank you.
00:07:41Just so we make you look good on, you know, the little camera thing.
00:07:45Camera one and camera two. Yes.
00:07:46What cameras?
00:07:47There's two cameras?
00:07:49Fade to Audrey. There we go.
00:07:51Okay. Let's get them separated, get the covers off, and find a space in the sun. Audrey?
00:07:58What time is it?
00:08:00Stop. Stop.
00:08:02And it'll probably be about 1:30 or 12:30 when we have them set up out there.
00:08:11That's beautiful.
00:08:16(You have a) compass right there.
00:08:19Okay, put circles on both data pieces, today and tomorrow.
00:08:26Put sunspots at the top, name, date, and the period, and the time of 12:30, which is about when we will be out there.
00:08:33Mr. Melville? What time-
00:08:35What time-//how- how-
00:08:36//Can we go out there when we're done, Mr. Melville?
00:08:37Well, we're all- we're all heading out there.
00:08:42Okay. Tops off. Let's get the stands from the telescopes and head on out.
00:08:46(inaudible) //My temperature is 102.
00:08:47//Okay. Gather your stuff.
00:08:49Okay. Seriously? That's probably why you don't feel well, Randy.
00:08:51What happened to Randy?
00:08:52He's got a temperature of 102. So that's probably why he doesn't feel well.
00:09:04Let's go, folks. Bring them outside. Find a spot in the sun.
00:09:18Goodie, goodie.
00:09:33Let's do it right here.
00:09:34Where's Kevin at?
00:09:37The sun's right here.
00:09:38Where did you see that? I never told him that- or told her that you liked her. I never said that she liked John.
00:09:46Mark your sunspots and track one moving west, please.
00:09:52Come on, you guys. Everybody else is out. Let's go.
00:09:54Come on.
00:10:03Hurry up.
00:10:05Hurry up.
00:10:09Hurry up.
00:10:10Please be careful with them. Come on, Miguel.
00:10:13Okay. Wait.
00:10:16I'm learning very quickly.
00:10:20Very slowly.
00:10:21Okay. Any of these areas in the full sun is fine as long as you're not behind tree shadows.
00:10:25Right here.
00:10:26That would be fine. That- that's fine.
00:10:28Cindy? Cindy? Cindy?
00:10:33No. We're going over here. Look, I didn't write-
00:10:39I have it right here.
00:10:40It needs- Monica, //it needs a little adjustment just so it'll get it more centered.
00:10:41//We can do it here, but it's not gonna show.
00:10:47Are you in my group?
00:10:59Mine's not working very well, Mr. Melville.
00:11:02You're getting it.
00:11:03Not really.
00:11:05Did you make the shadow disappear on the (inaudible) first?
00:11:07I don't no.
00:11:10There should be no shadow up there. So can you tilt it left and right //so that the shadow goes away?
00:11:14//What are you doing? You're not supposed to screw it.
00:11:17No, //you're not.
00:11:18//Diane, I need help.
00:11:19You're not?
00:11:20No. You're supposed to be able to move it around.
00:11:22Okay, now you got shadow on this side, okay?
00:11:25You're almost there. Now you just need to tilt it a little bit to make- there you go.
00:11:31Now, you should be able to see spots here. If you line those up in the center of the target, you should have your sun.
00:11:40There it is right there.
00:11:42Little sunspot.
00:11:43(inaudible) need small adjustments.
00:11:54And you're all set.
00:11:57Please mark your sunspots and track one of them moving west. Yeah?
00:12:01Can I get a drink of water because my-
00:12:02Sure. There's a sink right over there- I mean a faucet right over there.
00:12:06I can't see them (inaudible).
00:12:08Mr. Melville, is this a sunspot; the big one right there?
00:12:11This just doesn't work with my //(inaudible)
00:12:13//I don't think so.
00:12:16Are you serious?
00:12:18Flip it around.
00:12:19Are you talking about this thing right there?
00:12:21I think that's just, uh- stuff on your mirror or your lens.
00:12:26Done yet?
00:12:29Mark the other ones over there.
00:12:30It's the small black specks you're //looking for.
00:12:31//Hey, Miguel. It's the group.
00:12:35Where's Randy?
00:12:38Are you guys done yet?
00:12:39I am.
00:12:41Mr. Melville, I need help.
00:12:42Okay. Did we get them tracked west?
00:12:48No //(inaudible).
00:12:49Did //we? Okay. So you guys haven't done yours yet?
00:12:51We just started.
00:12:54Okay. Well, you're really close. See these white spots here?
00:12:58Okay. All I need is in the center of the target, see.
00:13:05I didn't know that.
00:13:07That's it. So there you go.
00:13:10So that was for-
00:13:11Now you need to mark them.
00:13:14Oh, that's ours?
00:13:17Where's yours?
00:13:18Right there.
00:13:19Okay. Are we gonna mark our sunspots and track them west?
00:13:23Track them west?
00:13:25You need to track one of them moving west.
00:13:27I'm done.
00:13:28Like we learned how to do on Monday.
00:13:29Oh, okay.
00:13:30Then we go put them back together?
00:13:31Just wait. We'll all go back in in about a minute or so.
00:13:35Wait. We got to find out which way is west.
00:13:40South, east, west.
00:13:50Audrey, what are you doing going into other people's classrooms?
00:13:53I'm not.
00:13:55You're standing there with the door wide open. What are you doing?
00:13:58Because Beatrice was talking to me and Brenda.
00:14:01Stay away.
00:14:02Ladies? Come here.
00:14:04I'm done.
00:14:05That's great. Did you find- you didn't get one moving west.
00:14:08Yes, I did.
00:14:09No, you didn't.
00:14:11What's west?
00:14:12The direction that the sunspots move.
00:14:13When you put it on there-
00:14:16When you put it on there, you're supposed to let the sun move and make a mark for one of your sunspots as it moves.
00:14:22It was this one.
00:14:23Then how come there's not a series of marks?
00:14:25Because I didn't leave it there.
00:14:26Okay. You got to mark them, and that way will show you the direction west.
00:14:35Hey, folks. You got to mark not only your sunspots.
00:14:38You also have to track them moving west so you know which way your image is oriented so please track one of your sunspots moving west.
00:14:50Mr. Melville, which way is west?
00:14:52Well, that's what you got to figure out on the-
00:14:54Wherever the sunspots are moving.
00:14:55Where the sunspots are moving is west.
00:14:57I know. I (always) make a little arrow.
00:14:59Okay. Well, then that would be west. That would be fine.
00:15:09Are you guys about finished or are you just goofing off?
00:15:12We're just about finished.
00:15:14(Just set it down in the middle.)
00:15:17(inaudible) my-
00:15:18All right. They just copied it all off of you instead of actually doing it? Oh, that's so helpful. Okay, folks.
00:15:29Let's get your telescopes and bring them back in.
00:15:39One of you guys get the other half, Cindy.
00:15:50Put them together, get the covers on, bring them back up to my desk.
00:15:54Okay, then-
00:15:55Audrey, why?
00:16:07Matt, Rupert. Come on, you guys.
00:16:23Esther, who's sitting out there still?
00:16:26Hey, Ian.
00:16:27Come on, Ian.
00:16:29Ian? Al puerta. Come on, doggie.
00:16:34Don't, Miguel.
00:16:35That's enough, Miguel.
00:16:41That's funny.
00:16:48Let's get them back together, cases on. Bring them up front.
00:16:58Justin, would you collect all the compasses?
00:17:00Please send the compasses to the front of the room so Justin can pick those up.
00:17:11Don't just throw it, Audrey.
00:17:14Audrey. Audrey.
00:17:18I'll take it. Thanks.
00:17:27My name is Justin.
00:17:29Justin. Justin Timothy.
00:17:33Justin Timothy. Timothy. Justin Timothy.
00:17:40Oh. This is your (inaudible) class?
00:17:42Uh, last year, yep.
00:17:43So was Muriel, huh?
00:17:44Yep. She was in my algebra class.
00:17:49We gave stuff away in there, huh, Muriel?
00:17:52Last year's algebra class.
00:17:54Just like gave you stuff, remember?
00:17:55Oh, yeah.
00:17:57Yeah. She's looking at you in the picture.
00:18:04Like candy bars and sodas, remember?
00:18:10I need you guys to take out the lab sheet that we went over yesterday, please.
00:18:31I remember somebody paid like three thousand dollars for a cup of soup or something like that, remember, in the secret bags.
00:18:38Remember the ones we rolled up and stapled shut. That was funny.
00:18:40I need one.
00:18:41They're on the counter up here. Folks, get your labs. Find your spots, please.
00:18:49What the (inaudible)?
00:18:51Carly, watch your mouth, please.
00:18:53Okay. Sorry.
00:18:55You want to die there? (inaudible) here?
00:18:59Matt, find your seat.
00:19:05And you're telling the teacher why?
00:19:12They go in the bag on my desk. Can you do that for me, please. Shh.
00:19:18Always in my face.
00:19:19Oh, my gosh.
00:19:21Okay, folks. I need your attention up here, please.
00:19:23I wasn't jamming it. Oh, my God. (inaudible).
00:19:41Okay. Everyone should have the "Pulley Potpourri" sheet out in front of you; the lab sheet.
00:19:46Who thought of that name?
00:19:48I did. It's my lab.
00:20:16Shh. We're gonna get started on the lab today.
00:20:23Shh. Folks, I need your attention up here, please.
00:20:28I'm glad you guys are having so much fun coloring inside the letters, but (if) I could get your attention up here, I would really appreciate it.
00:20:39We went over this yesterday. I'm just gonna recap it today because it's been 24 hours, and I know you forgot.
00:20:48You're just gathering three pieces of data from each pulley setup.
00:20:53You're gathering the effort distance, the effort force and the resistance force.
00:21:00As I went over yesterday, you measure the resistance force just by picking the weight up with the scale,
00:21:10and you measure the effort distance by using the ruler in centimeters to measure how far you pull the string
00:21:20when you lift the weight by 10 centimeters.
00:21:23The resistance distance in every case is 10 centimeters.
00:21:28If I can have your attention back here-
00:21:33just quickly go over this for the first setup again.
00:21:36There are two rulers back at the station.
00:21:44You'll be using both of them at the same time.
00:21:47One person is gonna be measuring resistance distance; one person is gonna be measuring effort distance.
00:21:53So you'll have one person using the centimeter side of the ruler. There's an inches side.
00:22:00Don't use the inches; use the centimeters. They're gonna be measuring how high the bottom of the weight goes up.
00:22:07When it's at 10 centimeters, that's as far as you're going.
00:22:11While they're doing that, the person applying the effort to the simple machine, the person pulling on the string,
00:22:20is gonna be measuring how far they have moved the string to raise the weight ten centimeters.
00:22:28Now, some people in earlier classes were just writing down the numbers on here.
00:22:34They would just- be holding them here and go, "Oh, that's 55."
00:22:37That's not how it works. It's how far it moves.
00:22:41So when the person is reading the resistance and they say, "Oh, that's 10 centimeters," on this thing, then you'll stop.
00:22:48Where did you start? Where did you end?
00:22:51If you started at 55 and went to 60 or went to 45,
00:22:56depending on how you turned, how far would that be?
00:22:59Say, you started at 55, and you pulled the string down to 60 on the ruler. How far would that be?
00:23:06It would be five centimeters. Say, you started at 55, and it went to 45. How far would that be?
00:23:12Ten centimeters.
00:23:13It would be 10 centimeters. So it's how far you exert the force.
00:23:19Audrey. It's the distance over which you apply the effort.
00:23:26That's what effort distance is.
00:23:28So if you start here and extend it that far, that's the effort distance.
00:23:33A couple things to be aware of when you're doing your measurements.
00:23:37If you pull it at an angle, your measurements won't be very accurate
00:23:41so you want to make sure that you're pulling straight down in the direction that you are measuring.
00:23:47Secondly, you want to make sure that, uh, when you're measuring the force you're also pulling straight down.
00:23:54Straight down really helps on this lab. All right. So that's effort distance.
00:23:58Probably one of the harder things to measure in the lab. We went over- we went over resistance distance.
00:24:05What is it for every experiment that we're doing?
00:24:09That's force, as in Newtons. But what's the resistance distance? Look on your lab. It's already filled out.
00:24:16Ten centimeters.
00:24:17It's 10 centimeters. So 10 centimeters is how far we're lifting the weight up.
00:24:21How far we pull this to lift the weight 10 centimeters is our effort distance.
00:24:25The forces- I went over those yesterday. Got to zero these things.
00:24:29The resistance force is just how much the resistance weighs, and as you guys just said a second ago, we are measuring it in what?
00:24:37We are measuring it in Newtons. Estimate to the closest quarter Newton.
00:24:41For effort distance- again, I showed you that yesterday- you need to tie a loop in the string, you need to zero it out upside down,
00:24:49and you're gonna pull, and it works again much better if you pull upside down.
00:24:54If you pull upside down- I'm sorry. Not pull upside down.
00:24:56Pull straight down. If you pull straight down, you'll get much more accurate measurements.
00:25:01If you do it off to the side, it just, uh- it's not gonna be as accurate, and again estimate to the closest quarter.
00:25:06Those are the only three things you're doing for each pulley setup. There's four pulley setups.
00:25:11You're not gonna get them all done today. You might not even get the first one done today. That's okay.
00:25:17It's better that you get accurate data than that you just rush through all of these. We got time.
00:25:22We're gonna spend a number of days on this.
00:25:25Mechanical advantage, lastly. When we've got all your data, we're gonna go back and do mechanical advantage,
00:25:31but you gotta- have to have good data so don't worry about mechanical advantage yet.
00:25:35All right. At this time I'm gonna divide you up into 10 groups and send you to a station.
00:25:40Get started on- well, you can do any of the pulley setups you want.
00:25:43It doesn't matter whether you start with the first one or not, but let me sort of divide you guys up here.
00:25:53That'll actually work out just, uh, fine.
00:25:57Cindy, I'm gonna go ahead and, uh, put you and Matt with Miguel, and you guys will be at the first station over there.
00:26:04Don't kill each other. Um, Diane, you guys are gonna be here on the other side of this first station.
00:26:11Cassandra, you guys will be on this side of the first station.
00:26:13Carly, you guys will be across from Matt's group. Audrey, you guys will be at this third station over here. Rupert?
00:26:22You guys will be just across from that.
00:26:27Sheila and Eleanor, you guys will be where Cindy is, working at that station.
00:26:31And, Josh and Muriel, you'll be just across from that.
00:26:35And- let's see- Andrew and Zeb, you guys will be at this station back here, and you guys will be at the very last station on the end.
00:26:42Okay. Let's head to our stations. Take your data table. Let's get them set up and get to work.
00:26:47How much are these worth?
00:26:49I think those were worth 50, but-
00:26:54is there anything over 50?
00:26:57I don't know.
00:27:00I think it was just 50, so-
00:27:04Go ahead and put 50 on there.
00:27:18There are knots in your string other than the one at the end.
00:27:22You're gonna want to get those out. They don't go over the pulley well.
00:27:27Are we right here?
00:27:29All right.
00:27:37You guys are sort of working at different ends here, okay?
00:27:41Like this?
00:27:42You probably want to put the loop through. It doesn't- it doesn't really matter.
00:27:47But the loop hooks onto the weight. It's just you have to pull a lot more string through if you put the- better bring the string through first.
00:27:56You can't just go like this and then-
00:27:58Sure. You can. That's fine.
00:27:59Put that weight up.
00:28:03(You can ask me more, like, gently.)
00:28:05Right here.
00:28:06Where's the weight? This hooks around it?
00:28:10Yeah. This hooks through.
00:28:14//It falls off.
00:28:15//You got to keep the string on the pulley though.
00:28:17Mr. Melville?
00:28:22Do you want us to do something with 41- the 41 part?
00:28:27I have no idea what you are talking about.
00:28:30How do we do effort force?
00:28:32You tie a loop in the string and pull down when you're lifting the weight up.
00:28:36And see what reading you get.
00:28:39What do you want?
00:28:44How did you get effort distance on there, Zeb?
00:28:47(This side)?
00:28:48You just- yeah. You need the difference.
00:28:53So what's the difference between 57 and 41?
00:28:58We need, uh- where is the ruler?
00:29:00That thing-
00:29:02Oh. Where-?
00:29:04(inaudible) this thing, that we went to yesterday-
00:29:08'Cause that's what they said to us. They said that-
00:29:09(shall I) measure it?
00:29:11She has to measure how far hers went while you're measuring that.
00:29:19Actually, the up-
00:29:23Sheila, you're measuring how far your hand moved while she lifted that.
00:29:30You want to- you want to start with it on the ground and start at something even, and when she says:
00:29:36"Oh, that's 10 centimeters," then you look at how far you went.
00:29:41All right.
00:29:43Oh. Is that effort distance?
00:29:44So you start- it's how far the effort string goes. Yeah, that's effort distance.
00:29:47Mr. Melville?
00:29:49What is it if it is from 50 to the one right here? Do we count one, two, three, or these little ones?
00:29:53Well, the little ones are what? The big ones are centimeters. What are the little ones?
00:30:00Okay. They are millimeters, or tenths of a centimeter. So it would be- it would be point something.
00:30:05You are trying to measure accurately, yeah. To the tenth would be fine.
00:30:18You're gonna flip it.
00:30:20I'm confused.
00:30:22Which one?
00:30:23All right. Put your hand up there somewhere.
00:30:25What are we supposed to do? Just pull up and be like: "Woo, look how far it went?"
00:30:28Yeah. That's it.
00:30:30No, seriously-
00:30:31You're supposed to actually measure some stuff along the way, and what would that be?
00:30:34//Then what do we do after that?
00:30:35//Wait up. Dude, just leave it this.
00:30:37What's that?
00:30:38Hold it, Audrey.
00:30:39All we do is pull it up? That's it?
00:30:43Hold it.
00:30:44And how far are you supposed to //lift it?
00:30:45//Hold it. That girl-
00:30:46Ten centimeters.
00:30:47Okay. So when that's being lifted 10 centimeters, you want to know how far //you had to pull this down.
00:30:50//That's what I'm saying. Hold it.
00:30:53Which means you need to-
00:30:54Where do you start from?
00:30:55you need to measure. You can start from anywhere you want because it matters where you go to.
00:31:01So I'd start at something even.
00:31:03But it has to be straight down, and you have to know where you started. Audrey. Audrey, it's gonna fall.
00:31:08Start at 60.
00:31:09All right. Hold it from up here.
00:31:10But you got to hold it somewhere so that you can pull.
00:31:13Okay. Ready?
00:31:15Oh, my god. You're //supposed to hold this right here.
00:31:17//You got to measure- measure it while you do it, Audrey.
00:31:20You do it.
00:31:23How do we (inaudible)-
00:31:24It's so frustrating working with a blonde.
00:31:25Don't worry about that yet. We're gonna do that together once we got our data.
00:31:29Audrey, just measure while you pull down.
00:31:31I don't understand it.
00:31:32Come here.
00:31:33You have to write on this page, okay? Just this page.
00:31:36I wrote there.
00:31:39Audrey, let's say you started there, and by the time that thing was 10 centimeters off the ground you were here. How far did it move?
00:31:49I know how-
00:31:50//How far did it move?
00:31:51//I understand it.
00:31:52I started at 50, I went down to 44. How far did it move? Or you can do it this way if you like that better.
00:31:59Yeah. Just take my pen.
00:32:00Started at 50, and I went to //64.
00:32:01//I don't mind.
00:32:02How far did it go?
00:32:03Ask him.
00:32:04Ten. Twelve.
00:32:05Fifty to 64 is ten?
00:32:07Okay. So it would have been 14 centimeters, right? That's all you're doing. But you're-
00:32:11But then where do you write it down?
00:32:12I know.
00:32:13Under "effort distance."
00:32:14Okay. We need your help.
00:32:16But guys, I wasn't doing it for you. It was just an example of how to read it.
00:32:19That's what I'm saying-
00:32:21I don't know how-
00:32:22You can't write down 14.
00:32:23When this is 10 centimeters off the ground, you want to know how far this string was pulled to lift this 10 centimeters off the ground.
00:32:32That's what you're measuring.
00:32:34Mr. M.?
00:32:36Ian, go back to your spot.
00:32:37We need to show you.
00:32:39You can't show on the other side //measuring (inaudible)?
00:32:40//Mr. Melville, I don't //get this.
00:32:41//How do you do effort force?
00:32:43Tie a knot in the string.
00:32:45Pull it with the scale. Read the reading in Newtons.
00:32:48Oh. Okay.
00:32:49So- thanks.
00:32:51We need to pass this back?
00:32:53Uh, yeah. Pass everything back. That's cool. Thanks.
00:33:02Mr. Melville?
00:33:03What's that?
00:33:06Uh, I- it's been- it's been in there for a while. I've already seen it so yeah.
00:33:10Take it right here?
00:33:11Yes, ma'am.
00:33:12He called me first.
00:33:15Like on this again- because we were doing this on this and we hooked it up to here.
00:33:19I mean- //I mean, I was listening to you but I kind of-
00:33:20//We did this. We did that.
00:33:23You need three pieces of data. Weigh this thing. That's resistance force.
00:33:26Off this?
00:33:27Tie a loop here, pull it down with the scale. That's effort force. Lastly, lift this 10 centimeters off the ground by pulling here.
00:33:36And measure how far you pull this to lift this 10 centimeters off the ground.
00:33:43This is the effort into my string so how far I pull it is gonna be what?
00:33:47Ten centimeters, isn't it? Same as the bottom.
00:33:49Well, that's what you are gonna find out.
00:33:50Oh. Okay.
00:33:51But you're gonna find that for most of the (pull) setups it's not the same, okay?
00:33:55Tie it up here?
00:33:57No- yeah, for the force, yeah.
00:34:00So we're doing a weight on it?
00:34:02Wait, wait, wait. Hold on. Hold on. Hold on.
00:34:05Okay. Which part are you guys stuck on here?
00:34:07We don't get the whole thing because-
00:34:08I know.
00:34:09Resistance force- wait.
00:34:10Okay. That's where you just //pick up- pick up the weight.
00:34:11//Four and a half pounds.
00:34:12It's not pounds. What is it measured in?
00:34:16Four and a half Newtons.
00:34:20Four and a half.
00:34:21It's not four and a half.
00:34:22It's halfway between four and six. That's not four and a half.
00:34:25Oh. Five.
00:34:26What are we measuring though on this?
00:34:28You're measuring three things. Vincent just did one of them.
00:34:31Yeah, but-
00:34:32Okay. You- you- you're //sure you have it zeroed before you start it?
00:34:33//Well, what is this one-
00:34:36I'd ask the same question to Vincent, too.
00:34:38When it- when it's not hooked up, is it at zero? No, it's not.
00:34:44//So you want to adjust it so that it is in fact on zero when you start.
00:34:49So that's resistance force. Effort force, when the weight is on here-
00:34:54It's like Newtons.
00:34:55Tie a loop.
00:34:56I got four and a half.
00:34:57Pull it down. Read what the force is on the scale.
00:35:00I don't get what you're saying, "set it to zero." Like, it can't move.
00:35:04Okay. This thing goes up and down.
00:35:07Oh, I didn't see that.
00:35:08Put it so it's on zero. Yeah?
00:35:09How do we set it up for that one?
00:35:12Do we have to set it up-
00:35:13You need to tie it up here.
00:35:15You need a pulley here.
00:35:17A weight here. There's a loop of string up here.
00:35:20That connects your pulley to your weight.
00:35:23The string from the bar goes through the pulley and up.
00:35:26Just like it looks in the picture.
00:35:27Do you have any tissues?
00:35:28Uh, no, but I have paper towels over by Diane there so- I think the tissue box is all empty.
00:35:38Okay. What do we do with this?
00:35:40That's how- what you measure the forces with.
00:35:43So it's this one and that one?
00:35:45It's- you're gonna use it to measure //resistance force and effort force.
00:35:48//now look, Mr. Melville-
00:35:49We got four and a half.
00:35:51When I did that, I started out at 50 and I ended up with 60 so //what would I write?
00:35:54//Okay. So it would be how many centimeters?
00:35:56Ten centimeters, yeah.
00:35:57So where do I write that one? On effort distance?
00:36:01Effort distance, yes.
00:36:02Wait, four Newtons.
00:36:04Four Newtons.
00:36:07Four and a half.
00:36:08We put that on.
00:36:09Now, did you have it zeroed before you weighed it?
00:36:13Okay. It should be at zero, and you'll see that it's way above the zero.
00:36:17You actually just slide this up and down to get it on zero.
00:36:20Oh. Okay.
00:36:23You're gonna want to get the knots out of that when you're done, too.
00:36:32It's not four and a half Newtons. Look. It's almost six.
00:36:35It's four and a half.
00:36:36It's almost six. Look. Watch.
00:36:37You have to make sure it doesn't move.
00:36:41That's far away. You're supposed to stay with four.
00:36:42Isn't it almost six?
00:36:46That's probably way too far.
00:36:48Ours is six-
00:36:49Mr. Melville?
00:36:51Which one is the effort force?
00:36:52How do you do the mechanical advantage?
00:36:53You want to take this off, but don't worry about that 'till later. We're gonna do- do it all together.
00:36:57All right.
00:36:58You want to take this off of here because- yeah. You need the knot out of that, too.
00:37:04You- you need this off the weight. You- instead of being looped around here, you need it looped around up here.
00:37:08Because it's supported from the top.
00:37:14Mechanical advantage.
00:37:17How do we find the effort points?
00:37:20When your weight is on there, you need a loop here.
00:37:25With the weight off the ground, hook the scale up, so that you can read on the scale.
00:37:34Audrey, what you working on?
00:37:42Audrey, what you working on?
00:37:45Did you help Ian out with //the lab setup?
00:37:47//Mr. Melville?
00:37:49What do you write for (here)?
00:37:50The force- distance and force?
00:37:53And effort force?
00:37:55Okay. Effort //force-
00:37:56//And mechanical average?
00:37:57Effort force. Don't worry about mechanical advantage yet.
00:38:01For effort force-
00:38:08you need to tie a loop here in your string. You need to lift it off the ground-
00:38:13You said not to tie anything.
00:38:15No, I didn't. I said, "Make sure the knots are gone when you're done."
00:38:19I specifically told you to tie a knot here because you're gonna hook this up to it and lift it off the ground and read the effort force.
00:38:25That's effort force. The effort distance is how far this moved in lifting this 10 //centimeters off the ground.
00:38:33//Okay. I got you.
00:38:34So you are gonna have one person measuring that it's 10 centimeters, the other person measuring how far their fingers moved //when they did that.
00:38:39//This is for Andrew.
00:38:42I told you.
00:38:44You //didn't tell me anything.
00:38:45//Mister- Miss Isaac sent him in.
00:38:47Miss who?
00:38:48Miss Isaac sent him in.
00:38:50Oh. It's from Miss Isaac. Okay.
00:38:55Do I got two of them?
00:38:57No. Just one.
00:38:58Just Andrew?
00:39:00You got stuff to work on, dude?
00:39:02Okay. Come here.
00:39:03Richard, you're still (inaudible).
00:39:06Thanks. You can work right there. That'd be fine.
00:39:11Hopefully we'll never have to use this.
00:39:13Yes, except when subs are here.
00:39:17This counts as a homework stamp, right?
00:39:20What's that?
00:39:21This counts as a homework stamp, right?
00:39:22I have no idea why that's on there. What is that on there?
00:39:25Yeah. //I wonder why.
00:39:26//Is that the day you couldn't find a blank piece of paper and I stamped that on there for you?
00:39:30No. It's- //I don't know (inaudible)-
00:39:31//Because there are no more-
00:39:32Okay, look at (inaudible). Let's do this.
00:39:34Okay, I'm gonna bring it up, //and you measure 10 centimeters off of the table.
00:39:35//I don't remember stamping it either. I have no idea what that is.
00:39:38Mr. Melville? Mr. Melville?
00:39:41Andrew, you need to sit down. You need to sit down.
00:39:45Wait. It's not-
00:39:46That's 10 inches, not //centimeters.
00:39:48//You guys are seriously gonna want to //get that knot out of there.
00:39:49//We need to go inches.
00:39:50It really messes up the pulleys.
00:39:53Ten centimeters. //Centimeters!
00:39:54//No. No. I said you need to tie a loop to measure effort force, but you don't want any knots in the string. It messes up going through the pulley.
00:40:01You have to have your finger right here. Let go.
00:40:03You mean a loop like this, Mr. Melville?
00:40:05What's that?
00:40:06Like this?
00:40:07Bridget? What are we weighing?
00:40:10A loop, that circle thing?
00:40:11I don't understand what you're saying.
00:40:12Never mind.
00:40:16The only time you need a loop in there is when you're measuring the effort force. Other than that, the knot should be out of the string.
00:40:27That's fine. It has to be enough that you can- well, it should be on the pulley for one.
00:40:31Is Savannah here?
00:40:35I wasn't looking at that. I was-
00:40:36And then you have to pull down to make the weight go up. No, no, no.
00:40:40You want to pull down with the scale so you're actually measuring the force on the-
00:40:44So like this?
00:40:46You do it. I don't understand-
00:40:47There. There. That's it. Now pull down on the scale.
00:40:50On the scale?
00:40:51On the scale. Let go of the other string. There you go. That's it.
00:40:56But then you would be looking at it-
00:40:58Yes. You're gonna be looking at it upside down.
00:41:00I was, like, like four and a half.
00:41:01I get what you-
00:41:02There you go. Yeah. Now, untie it when you're done.
00:41:05Four and a half?
00:41:06So I go like this, right?
00:41:07Where's my pen?
00:41:08Yes. But you want to do it straight down, because if you do it at an angle, it gives you a slightly different reading.
00:41:13Six Newtons.
00:41:18Six Newtons.
00:41:22Why do you tie that around?
00:41:25What do you need to do for this?
00:41:27You need to tie your string at the top, attach your weight directly to the pulley with this little loop of string that I put up here.
00:41:36And then you need to run your string through the pulley and up, and you'll be lifting in an upward direction for that one.
00:41:44You didn't see the pulley. Lift the (rope).
00:41:47Yes, ma'am.
00:41:48Yes, ma'am?
00:41:49I said, "Yes, ma'am."
00:41:50Oh. I see. I see. Wait. No. Wait. No. No. Not that. We already pushed that.
00:41:54Yes, ma'am?
00:41:55Mr. Melville, //my loop isn't very good.
00:41:56//(inaudible) and it's 38 centimeters. Where do you put it? I forgot.
00:42:00What's 38 centimeters?
00:42:02The (inaudible). This.
00:42:03No. No, no, no. It's not- it's how far you moved it.
00:42:07Yes, I did.
00:42:08No. It's how far you moved it in raising it 10 centimeters. So start somewhere even like 50.
00:42:15Marcello? Measure the weight. Measure the weight and tell me when it's 10 centimeters off the ground.
00:42:23How do you tie a knot?
00:42:25Right there?
00:42:27Okay. I'm at 60 now. Where did I start?
00:42:29I started at 50 so how far did I pull up?
00:42:30Ten centimeters.
00:42:31There you go. That's what goes in this first spot.
00:42:34The distance that you moved //the effort string.
00:42:36//The effort distance?
00:42:37The effort distance, yeah.
00:42:40We did- we already did this one. How do we do this?
00:42:45You're gonna tie- tie your string to the top. Actually, you can just loop it through, around.
00:42:52It's gonna go down, through the pulley. The pulley will be attached with this little loop directly to your weight.
00:43:00I don't get it. Can you show me again?
00:43:01No. I- look at the picture. I want you to look at the picture and set it up like the picture.
00:43:05We finished all those (inaudible)-
00:43:06You finished all four of them?
00:43:08Not all four-
00:43:09or you finished the first and second?
00:43:11Can I see your data?
00:43:17Is it the last one, Zeb?
00:43:21You guys were able to get the first and second ones done?
00:43:25Who? Us?
00:43:26It's us.
00:43:27Oh, it's you guys.
00:43:29What did you do?
00:43:32Look at this.
00:43:34The effort force was 16 Newtons?
00:43:41Sixteen... oh, 16 centimeters.
00:43:44Okay. That would be effort distance.
00:43:48Okay, we can go on.
00:43:49Okay. The resistance force, how did the weight get- your weight was three Newtons both times?
00:43:56Which weight do you guys have? Oh. You guys have the brown one, right?
00:43:59Okay. So that one's different.
00:44:00Okay, the one thing you didn't do then on- on, uh, either of these setups is correctly figure out the effort force.
00:44:09That's the one where you tie a knot in the string,
00:44:11//Oh yeah, we got to do (this)
00:44:12//hook the scale up to it and pull.
00:44:15We did it on this one, and we got 12.
00:44:16No, you didn't.
00:44:22And does that say 16 also? Okay. That one's not right either.
00:44:26When you lift this off the ground by 10 centimeters- Miguel, stop it.
00:44:35When you lift it off the ground by 10 centimeters, how far did this string move? That's what you need to measure.
00:44:40Oh. Okay.
00:44:42Okay? I don't think you did it right either place.
00:44:45This is hard. We need Will in here. He's a smart boy.
00:44:49You took my stool.
00:44:50When you get it set up again, call me over. I'll //show you.
00:44:53//All right.
00:44:56Can you help us with part two?
00:44:58Okay. Whatcha stuck on?
00:45:00We don't know how to do this thing. We're not-
00:45:01Okay. Well, look at it. Your string should be tied to the top bar. Do you see that in the picture?
00:45:10Well, you- you can loop it through just like you-
00:45:14Oh no, well look.
00:45:17Here, I'll give you one hint. Hand me the other end.
00:45:25Oh, (it will) slide through.
00:45:33It's the same.
00:45:38Then you hook the pulley directly up to the weight like it shows, run the string through the pulley.
00:45:43That little loop of string- yeah. That's how you do that part. Ian, you gonna do anything today?
00:45:48I already-
00:45:49I already did one.
00:45:51I did practically everything.
00:45:54//Oh, thank you.
00:45:55//How do you do this part?
00:45:56Can I actually look at it where I can see it.
00:45:57How do you do mechanical advantage?
00:46:00We're gonna do that one together. What //was-
00:46:02//(We got) 25.
00:46:03What was 25?
00:46:04That's what I told her.
00:46:05Where does it say 25?
00:46:07On 23 or whatever that says. What is that?
00:46:10That says 23.
00:46:11So where did that come from? Did //you just make that up?
00:46:12//You take 12, six- oh, wait. I forgot to add 10, huh? Okay. It's- it's 33.
00:46:18Because I added it all up.
00:46:21Watch out.
00:46:22Why not?
00:46:23Oh, so for this one we have to do-
00:46:25I don't know.
00:46:26It doesn't make any sense.
00:46:27Well, I don't know how else to do it. That's why.
00:46:29How do you do this part? The one where you put that-
00:46:33You broke it.
00:46:35No, I didn't.
00:46:36That's your effort force. You just pull that one down.
00:46:40Look it, Mr. Melville. We did it.
00:46:41Don, that's it. Perfect. Excellent job.
00:46:43Okay, folks. It's time to clean up.
00:46:46You get out of here when your stations look exactly like they did when you came //to the station,
00:46:51//Hurry up, hurry up, hurry up.
00:46:53So everything hung back neatly where it belongs.
00:46:57That was like this.
00:46:58And, uh- oh, can I have that (inaudible)?
00:47:01//After school.
00:47:02//Mr. Melville-
00:47:07You think someone can pick up our notebook?
00:47:09You're scaring me, Rosalie.
00:47:11Uh, Diane dropped her pencil down the drain.
00:47:14You did? Seriously? I have no way of getting it out.
00:47:18No one-
00:47:19It goes down- it goes down about six inches before-
00:47:21No one must see that book. Nobody.
00:47:24How about I read the whole thing between now and sixth-
00:47:27Don't do it.
00:47:29Just to remember. You come after school and you can have it.
00:47:32Um, what we're doing is we're trying to find the, um-
00:47:35//That looks perfect.
00:47:36//resistance from the lift, //10 centimeters?
00:47:38But how do you calculate the effort force?
00:47:40Tie a knot in the string. Hook the scale through it and pull. Read what you get on the scale.
00:47:46Oh. Okay. And- and we weigh- we already weighed it. It weighs five and a half Newtons.
00:47:50That's what- that's the force the gravity is pulling downward with.
00:47:53So resist-
00:47:54That's correct. That's the resistance force.
00:47:55And after that we just cut-
00:47:57No. Don't worry about that yet. We're gonna do that together.
00:47:59Okay. And it's the same thing here if we were to do it?
00:48:02Exactly. It's just a different pulley setup, but the calculations are the same.
00:48:06Oh. Okay.
00:48:09I thought I told you guys that yesterday.
00:48:11You said Friday.
00:48:12Right. Tomorrow's Friday. That's cool.
00:48:17Folks, seriously, your stations need disassembled, cleaned up, put back the way they were.
00:48:23I don't see a single station that's acceptable right now.
00:48:27That one is.
00:48:28Look at ours.
00:48:32You guys don't get to go until the station looks like it did when you got there.
00:48:39Are you serious?
00:48:41That's how it looked when I got there.
00:48:42That looks good.
00:48:43I know, huh.
00:48:46Everything neatly hung up on those corners like it was when you got there.
00:48:51Rulers lined up neatly on the table. No knots in the string. Please get them cleaned up.
00:49:03We couldn't get the pencil out of the drain.
00:49:05No. You won't probably be able to. I'm sure there's probably many, many things down the drain.
00:49:13You probably wouldn't want your pencil back after it'd been down the drain anyways. It's kind of nasty.
00:49:18Does this go in the closet?
00:49:23(Would you) get my pencil out?
00:49:26I think it went all the way down the drain, because it's not in there no more, Diane.
00:49:31There's a- there's a drain trap so it can't go past.
00:49:35Well, what if we took off that sink part and like-
00:49:38Well, we could. You just need a screwdriver and, uh, you need some pipe tape so when you put it back so that it seals again,
00:49:49and you could rescal- rescue her mangy old pencil.
00:49:53You need it desperately?
00:49:58Excuse me, //Mr. Melville?
00:49:59//Hey, folks. Let's stand up and get your chairs pushed under, please.
00:50:25Just push it under, but you don't get to go until anybody else goes. Okay, Andrew?
00:50:32Punch and munch tomorrow, not punch and munch and movie. Just punch and munch. You do have a quiz tomorrow.
00:50:37You might want to look over some of the stuff we've talked about this week like work and machines-
00:50:43What can we bring again?
00:50:44Anything except for gum, corn nuts, sunflower seeds and chips. Anything else is fair game.
00:50:48All right. I need Miguel, Matt, Ian, and Audrey. They owe me two minutes. The rest of you may go.
00:50:53What did I do-
00:50:54Miguel, you owe me 15 minutes at lunch, tomorrow.
00:50:57Expect to see you then.
00:51:00What did I do to get that-