WEBVTT 00:00:02.410 --> 00:00:05.400 A young man makes a projectile of himself 00:00:05.400 --> 00:00:07.840 this time from the mouth of a cannon 00:00:07.840 --> 00:00:09.950 a man fired through the air 00:00:11.852 --> 00:00:20.082 the universal laws of motion 00:00:22.025 --> 00:00:23.855 Bill Nye the Science Guy 00:00:26.754 --> 00:00:30.754 [ Bill Nye the Science Guy theme ] 00:00:33.739 --> 00:00:35.359 Science Rules 00:00:41.025 --> 00:00:43.515 Bill Nye the Science Guy 00:00:55.858 --> 00:00:57.798 Bought to you buy Pushy People 00:00:57.798 --> 00:00:59.848 when you need something moving 00:00:59.848 --> 00:01:00.918 call Pushy People 00:01:02.494 --> 00:01:04.284 Everything in the universe including 00:01:04.284 --> 00:01:07.044 you and me is in motion 00:01:07.949 --> 00:01:10.719 now forces put things in motion 00:01:11.055 --> 00:01:14.035 Forces like when something is 00:01:14.035 --> 00:01:16.715 pushed or pulled 00:01:17.481 --> 00:01:20.341 To understand motion you have to figure out 00:01:20.341 --> 00:01:25.111 if you are pushing on things or if things are pushing on you 00:01:28.056 --> 00:01:29.906 Let me show you what I mean 00:01:30.379 --> 00:01:31.899 We are right here 00:01:33.091 --> 00:01:34.881 but we were over there 00:01:35.359 --> 00:01:36.819 um over there 00:01:38.995 --> 00:01:40.085 here 00:01:46.135 --> 00:01:48.175 After I come through the door 00:01:48.223 --> 00:01:52.223 it looked like I was walking through the lab 00:01:52.263 --> 00:01:55.553 in a sense I was , but I was on a platform 00:01:55.839 --> 00:01:58.249 and I was standing over pretty much 00:01:58.249 --> 00:02:00.649 the same part of the main lab the whole time 00:02:00.927 --> 00:02:02.497 Till I fell off the platform 00:02:07.151 --> 00:02:09.651 You couldn't seperate the motions 00:02:09.651 --> 00:02:11.951 Now watch them both one more time 00:02:12.301 --> 00:02:14.811 Everything in the universe including you and me 00:02:16.037 --> 00:02:17.047 is in motion 00:02:18.571 --> 00:02:20.651 Forces put things in motion 00:02:20.651 --> 00:02:25.771 Forces like when something is pushed or pulled 00:02:26.777 --> 00:02:30.307 To understand motion you have to figure out if 00:02:30.307 --> 00:02:35.127 you are pushing on things or if things are pushing on you 00:02:37.271 --> 00:02:38.741 take a look at this 00:02:42.529 --> 00:02:44.149 This is an air track 00:02:44.149 --> 00:02:47.039 when the pump is running air comes out of these 00:02:47.039 --> 00:02:48.339 little holes 00:02:48.339 --> 00:02:52.339 and it can support the weight of a scooter like this 00:02:53.393 --> 00:02:55.873 Now when I place the scooter on the track 00:02:55.873 --> 00:02:58.143 and let go it just sits there 00:02:58.143 --> 00:03:00.543 it doesn't move unless 00:03:00.543 --> 00:03:03.163 I give it a push and it keeps moving unless I give 00:03:03.163 --> 00:03:04.543 it another push 00:03:04.543 --> 00:03:07.103 or it hits the end of the track 00:03:07.103 --> 00:03:09.513 or maybe another scooter 00:03:09.513 --> 00:03:11.693 another scooter, another scooter 00:03:11.693 --> 00:03:13.613 Now here's the thing if we had enough track and 00:03:13.613 --> 00:03:14.793 enough air 00:03:14.793 --> 00:03:17.493 The scooters would keep scooting forever there would be 00:03:17.493 --> 00:03:18.553 nothing to slow them down 00:03:18.553 --> 00:03:20.103 Well hardly anything 00:03:20.103 --> 00:03:22.593 So when something is at rest or sitting still 00:03:22.593 --> 00:03:25.573 it stays sitting still , unless acted on by an outside force 00:03:25.573 --> 00:03:28.383 If something is moving it keeps moving unless 00:03:28.383 --> 00:03:30.513 acted on by an outside force 00:03:30.513 --> 00:03:34.513 outside force , outside force , 00:03:34.513 --> 00:03:37.653 This is true of everything that you can touch and 00:03:37.653 --> 00:03:39.563 see as you may know 00:03:39.563 --> 00:03:41.453 Inertia is a property for matter 00:03:41.453 --> 00:03:43.133 Inertia is a property of matter 00:03:46.350 --> 00:03:49.230 A bowling ball weights more than a golf ball 00:03:49.230 --> 00:03:53.230 right now their weights are supported by these wires 00:03:53.230 --> 00:03:55.310 but if i push them or make them 00:03:55.310 --> 00:03:56.600 run into each other 00:03:56.600 --> 00:03:59.820 you can tell that the bigger one is harder to move 00:04:05.221 --> 00:04:07.451 We call this property of matter Inertia 00:04:07.451 --> 00:04:09.661 Inertia is a property of matter 00:04:13.988 --> 00:04:16.948 This is an anvil , it has a lot of Inertia 00:04:16.948 --> 00:04:19.478 now it's being acted on by an outside force 00:04:19.478 --> 00:04:23.478 Gravity 00:04:23.478 --> 00:04:27.328 But it's also being acted on by another outside force 00:04:27.328 --> 00:04:29.368 the pull of the chain 00:04:32.025 --> 00:04:34.685 Now to get an idea of just how much Inertia 00:04:34.685 --> 00:04:38.685 it has, we will lower it 00:04:40.424 --> 00:04:44.424 What's that noise.. Whoa Whoa 00:04:44.424 --> 00:04:49.894 Whoa Whoa Whoa 00:04:50.731 --> 00:04:52.571 Inertia , Whoa 00:05:05.631 --> 00:05:09.631 Now just for kicks , this is another type of air bearing 00:05:09.631 --> 00:05:12.351 the pump is on here 00:05:24.226 --> 00:05:27.156 Now gravity is still pulling it down 00:05:27.156 --> 00:05:29.606 and the air pressure is holding it up 00:05:29.606 --> 00:05:31.866 so those forces are in balance 00:05:31.897 --> 00:05:33.807 but the anvil has a lot of inertia 00:05:34.041 --> 00:05:37.041 and to get it moving we need a big push 00:05:37.793 --> 00:05:41.793 Oh no not this again , come on Bill please no !!! 00:05:44.325 --> 00:05:47.135 Whats Inertia , I'll show you 00:05:49.223 --> 00:05:52.373 Take a playing card and set it over a glass 00:05:52.373 --> 00:05:55.133 Set a quarter on top of the playing card 00:05:55.575 --> 00:05:58.245 Flick the card hard with your finger like this 00:05:58.245 --> 00:06:02.245 The card goes flying but the quarter falls into the glass 00:06:08.951 --> 00:06:10.441 The quarter has inertia 00:06:10.441 --> 00:06:12.721 it's not moving so it stays at rest 00:06:12.721 --> 00:06:14.421 but the card slide out so easily 00:06:18.434 --> 00:06:20.364 It doesn't overcome the quarters inertia 00:06:20.364 --> 00:06:21.874 so the quarter stays put 00:06:21.874 --> 00:06:25.064 of course once the card is gone there is nothing left 00:06:25.064 --> 00:06:28.564 holding the quarter so it falls into the glass 00:06:31.513 --> 00:06:34.123 whether something is moving or sitting still 00:06:34.123 --> 00:06:35.393 everythings got inertia 00:06:45.991 --> 00:06:48.381 Okay we got everything packed away 00:06:50.145 --> 00:06:51.725 Let's get'em on the truck 00:06:52.871 --> 00:06:54.661 Here boxes ,boxes, boxes 00:06:54.661 --> 00:06:55.771 [ whistles at boxes ] 00:06:56.331 --> 00:06:58.361 here boxes , come on 00:07:01.544 --> 00:07:03.634 I think you gotta get tough with 'em 00:07:05.163 --> 00:07:07.943 Hey boxes ! Hey . Get on the truck 00:07:15.623 --> 00:07:18.063 Hey why don't ya try a little psychology 00:07:20.620 --> 00:07:23.320 Hey , I hear they're giving out free ice cream 00:07:23.320 --> 00:07:24.870 to the first twenty boxes that get on the truck 00:07:31.042 --> 00:07:33.042 Hey , says here that nothing gets 00:07:33.042 --> 00:07:37.042 moved unless they get pushed or pulled 00:07:37.042 --> 00:07:40.452 Great ! Thats means we'll have to do the work 00:07:40.452 --> 00:07:42.552 Just like last time 00:07:46.344 --> 00:07:50.344 Please come on , boxes you're so heavy 00:07:50.344 --> 00:07:52.224 Come on on the truck , just out the door 00:07:52.885 --> 00:07:55.875 Newtons Laws of Motion 00:07:55.875 --> 00:07:57.935 First Law : The Law of Inertia 00:07:57.935 --> 00:08:00.225 Things at rest , stay at rest 00:08:03.749 --> 00:08:06.329 Hi Bill , I'm at rest 00:08:08.065 --> 00:08:12.065 Things in motion stay in motion 00:08:14.159 --> 00:08:16.509 Wee , I'm in motion 00:08:23.966 --> 00:08:26.746 Unless acted on by an outside force 00:08:28.270 --> 00:08:32.270 Second Law : To move a mass you need a force 00:08:33.998 --> 00:08:35.568 Here's a mass 00:08:36.480 --> 00:08:38.080 and here's a force 00:08:51.395 --> 00:08:53.255 and then in mathematics we say 00:08:53.255 --> 00:08:55.155 Force = mass x acceleration 00:08:55.756 --> 00:08:56.906 F= ma 00:08:57.969 --> 00:09:00.259 So in order to get the same mass 00:09:00.259 --> 00:09:04.259 accelerating twice as fast you need twice as much force 00:09:06.216 --> 00:09:09.226 Here's the mass and here's twice as much force 00:09:22.820 --> 00:09:26.100 The Third Law: For every action there is an equal 00:09:26.100 --> 00:09:28.150 and opposite reaction 00:09:28.383 --> 00:09:29.893 Action , Reaction 00:09:29.996 --> 00:09:32.546 Equal and Opposite , Action and Reaction 00:09:37.797 --> 00:09:41.407 Two masses , this one's going to be moving 00:09:41.639 --> 00:09:43.669 action , reaction 00:09:50.438 --> 00:09:52.868 One car moving , against two cars 00:09:54.384 --> 00:09:56.414 They move off half as fast 00:09:56.682 --> 00:09:59.212 Thats the equal and opposite reaction 00:10:00.924 --> 00:10:04.374 Newtons Laws of Motion 00:10:16.983 --> 00:10:19.583 Tonights episode , The First Law 00:10:21.227 --> 00:10:24.197 An object at rest remains at rest unless acted upon 00:10:24.197 --> 00:10:25.487 by an outside force 00:10:28.405 --> 00:10:31.205 An object in motion tends to stay in motion 00:10:31.205 --> 00:10:33.645 Unless acted upon by and outside force 00:10:43.963 --> 00:10:47.963 Let's watch that again in slow motion 00:10:59.635 --> 00:11:02.465 Without motion you're just a potato on the couch 00:11:14.043 --> 00:11:16.383 Street Luging is a highly modified 00:11:16.383 --> 00:11:19.313 version of skateboarding or butt boarding 00:11:19.313 --> 00:11:23.313 Get these babies in motion and there is no stopping it 00:11:24.442 --> 00:11:27.062 Let's do it , It's on 00:11:30.704 --> 00:11:32.984 We pushing along the ground to get us started 00:11:32.984 --> 00:11:35.444 and then we are under the wheel of gravity 00:11:35.444 --> 00:11:39.444 and the grade of the hill to determine our maximum velocity 00:11:39.444 --> 00:11:41.494 and our speed 00:11:51.549 --> 00:11:56.109 What we got here are weights ,our shoes and our life line 00:12:01.674 --> 00:12:05.364 That's after one run down a fifty mile and hour hill 00:12:05.364 --> 00:12:07.664 so got about two or three more runs outta those 00:12:07.664 --> 00:12:08.974 then get a new pair 00:12:10.213 --> 00:12:14.213 To have motion takes motion , you either got to push or pull 00:12:32.934 --> 00:12:34.984 Join the inertia dance project for 00:12:34.984 --> 00:12:38.104 a very special evening of movement and motion 00:12:38.104 --> 00:12:42.104 choreographer Isaac Newton sends his world 00:12:42.104 --> 00:12:44.574 premier piece entitled Bodies at Rest 00:12:44.574 --> 00:12:46.644 Stay at Rest 00:12:46.644 --> 00:12:51.484 mimes not admitted unless accompanied by a speaking person 00:12:54.351 --> 00:12:55.861 This apple has inertia 00:12:55.861 --> 00:12:59.521 it has mass right now the scale is measuring the 00:12:59.521 --> 00:13:01.341 pull of the earths gravity 00:13:01.341 --> 00:13:03.331 on the apples mass 00:13:08.617 --> 00:13:12.617 Here in the plane we have a lot of motion 00:13:12.845 --> 00:13:15.955 but the scale reads just about the same 00:13:15.955 --> 00:13:19.955 because the apple still has the same mass 00:13:25.079 --> 00:13:29.079 Now as we go down the apple is falling at the same 00:13:29.079 --> 00:13:31.739 speed as gravity makes it fall 00:13:32.240 --> 00:13:36.240 we are weightless , the scale reads zero 00:13:36.240 --> 00:13:39.580 but the apple is still the apple it still has inertia 00:13:41.993 --> 00:13:44.873 but now as we pull up the scale reads higher 00:13:44.873 --> 00:13:49.583 the plane is pulling you , me and the apple up against the pull of gravity 00:13:55.192 --> 00:13:59.192 we measure mass in grams or kilograms 00:13:59.192 --> 00:14:02.242 so if i do this the apple might be weightless but 00:14:02.242 --> 00:14:04.192 it wouldn't be massless 00:14:05.558 --> 00:14:09.558 Space-tone news presents ; the place space 00:14:09.558 --> 00:14:13.558 The question , In zero gravity do the laws of motion 00:14:13.558 --> 00:14:17.558 still apply. The answer yes 00:14:17.558 --> 00:14:20.858 objects in motion in space tend to stay in motion 00:14:20.858 --> 00:14:24.248 unless something slows them down 00:14:33.385 --> 00:14:35.295 Move ! Why won't you move 00:14:35.295 --> 00:14:37.345 Go back to where you belong 00:14:37.345 --> 00:14:38.905 Use the force 00:14:38.905 --> 00:14:39.705 Huh ? 00:14:40.920 --> 00:14:41.950 Use force 00:14:41.950 --> 00:14:44.780 an object at rest will stay at rest 00:14:44.780 --> 00:14:47.940 until an outside force acts upon 00:14:47.940 --> 00:14:49.820 use force Luke 00:14:56.511 --> 00:14:58.791 It worked 00:15:02.384 --> 00:15:04.784 So what did you learn in school son 00:15:06.662 --> 00:15:07.922 Nothing 00:15:10.442 --> 00:15:11.542 Son 00:15:12.834 --> 00:15:15.184 Okay , I'll show you 00:15:23.790 --> 00:15:26.640 See we learnt that objects at rest stay at rest unless 00:15:26.640 --> 00:15:28.640 of course they're pushed or pulled 00:15:28.938 --> 00:15:31.648 but this cloth because I jerked it so quickly 00:15:31.648 --> 00:15:33.968 couldn't push or pull any of the objects on the table 00:15:37.869 --> 00:15:40.809 By the way nice choice of cereal mum 00:15:42.659 --> 00:15:44.249 That's my boy 00:16:01.793 --> 00:16:03.693 Hey , it's lunch time 00:16:03.860 --> 00:16:06.980 oh okay… stay right here , don't move 00:16:17.900 --> 00:16:19.360 Sure is quiet 00:16:22.553 --> 00:16:23.293 Yeap 00:16:26.522 --> 00:16:28.692 Nothing moving for miles around 00:16:31.558 --> 00:16:32.418 Nope 00:16:33.542 --> 00:16:34.452 Pa 00:16:35.702 --> 00:16:36.752 Yeah 00:16:37.495 --> 00:16:39.675 There is something I gotta tell ya pa 00:16:44.922 --> 00:16:46.802 What is it Delilah 00:16:47.499 --> 00:16:51.219 That last statement you made isn't entirely accurate 00:16:51.732 --> 00:16:54.942 although to you the observer it appears that 00:16:54.942 --> 00:16:57.492 nothing is moving , well that is merely an 00:16:57.492 --> 00:17:00.102 artefact of your frame of reference 00:17:00.102 --> 00:17:03.512 Like right now the earth , it's spinning 00:17:03.512 --> 00:17:08.132 on its axis at about one thousand six hundred kilometres an hour 00:17:08.541 --> 00:17:12.271 and the earth is moving around that sun about 00:17:12.271 --> 00:17:15.051 thirty kilometres a second , plus our entire solar 00:17:15.051 --> 00:17:19.051 system here it's just hurtling around the outer edges 00:17:19.051 --> 00:17:23.051 of the Milky Way galaxy at one hundred and twenty 00:17:23.051 --> 00:17:23.941 kilometres per second 00:17:24.029 --> 00:17:28.029 not the mention the moment of our galaxy within the universe 00:17:28.029 --> 00:17:30.949 it's expanding at speeds approaching the speed of light 00:17:30.949 --> 00:17:34.949 that's about three hundred thousand kilometres per second 00:17:37.174 --> 00:17:40.184 So you see pa , we're all us here moving 00:17:40.184 --> 00:17:42.714 perrty fast 00:17:57.427 --> 00:18:01.427 [singing ] " We're all in motion 00:18:03.083 --> 00:18:07.083 We're all in motion 00:18:10.774 --> 00:18:14.774 Everything in the universe 00:18:14.774 --> 00:18:19.954 is all in motion 00:18:23.292 --> 00:18:28.302 When things are pushed or pulled 00:18:28.302 --> 00:18:32.302 They're put in motion 00:18:33.867 --> 00:18:37.867 The more the mass 00:18:38.057 --> 00:18:42.777 The more force we need 00:18:47.039 --> 00:18:51.549 The more inertia the 00:18:51.549 --> 00:18:58.309 the more force we need 00:18:59.429 --> 00:19:03.429 We're all in motion 00:19:03.544 --> 00:19:08.284 That's what it seems 00:19:15.295 --> 00:19:16.705 [ fast rock music plays ] I'm Bill Nye 00:19:42.378 --> 00:19:46.378 We're all in motion 00:19:46.378 --> 00:19:48.428 We're all in motion 00:19:50.564 --> 00:19:55.764 everything in the universe is all in motion 00:19:56.389 --> 00:20:02.999 When things are pushed or pulled they're put in motion 00:20:06.097 --> 00:20:07.637 The more the mass 00:20:07.814 --> 00:20:09.924 The more force you need 00:20:13.273 --> 00:20:14.983 The more inertia 00:20:16.207 --> 00:20:17.777 the more force you need 00:20:19.206 --> 00:20:21.496 We're all in motion 00:20:23.369 --> 00:20:25.459 That's what it seems 00:20:47.523 --> 00:20:51.523 [ slow music again ] We're all in motion 00:20:51.523 --> 00:20:56.113 We're all in motion 00:21:13.377 --> 00:21:17.377 Well that's our show thanks for watching 00:21:35.260 --> 00:21:39.260 If you'll excuse me I've got some third derivative jerk functions to evaluate 00:21:40.101 --> 00:21:42.181 See Ya 00:21:49.315 --> 00:21:51.925 ooo arrgghh never get used to it 00:21:52.081 --> 00:21:57.561 The dummy is no longer in motion 00:21:57.561 --> 00:22:01.561 produced in association with the National Science Foundation 00:22:02.680 --> 00:22:04.570 I love Science 00:22:05.163 --> 00:22:06.243 SCIENCE !! 00:22:06.771 --> 00:22:07.621 Yeah 00:22:09.812 --> 00:22:25.862 SCIENCE !!!! 00:22:27.092 --> 00:22:31.092 SCIENCE !!! 00:22:31.939 --> 00:22:34.009 It's science !!! 00:22:34.760 --> 00:22:35.580 SCIENCE !!! 00:22:36.351 --> 00:22:37.171 SCIENCE !!! 00:22:37.526 --> 00:22:38.476 SCIENCE !!! 00:22:38.881 --> 00:22:39.831 SCIENCE !!! 00:22:40.589 --> 00:22:41.509 SCIENCE !!! 00:22:42.553 --> 00:22:43.563 SCIENCE !!! 00:22:45.117 --> 00:22:46.377 SCIENCE !!! 00:22:56.683 --> 00:23:00.683 SCIENCE !!!