1 00:00:03,367 --> 00:00:04,901 FORCE IS PRETTY SIMPLY. 2 00:00:04,901 --> 00:00:06,400 IT'S BASICALLY JUST A PUSH OR A 3 00:00:06,400 --> 00:00:07,567 PULL. 4 00:00:07,567 --> 00:00:08,868 SO A FORCE IS A CHANGE IN 5 00:00:08,868 --> 00:00:10,801 MOTION. 6 00:00:10,801 --> 00:00:12,367 GRAVITY PULLS YOU DOWN, AND THE 7 00:00:12,367 --> 00:00:15,968 GROUND PUSHES YOU UP. 8 00:00:15,968 --> 00:00:17,234 WHEN FORCES ARE IN BALANCE 9 00:00:17,234 --> 00:00:18,434 NOTHING HAPPENS, AND YOU DON'T 10 00:00:18,434 --> 00:00:19,634 NOTICE IT. 11 00:00:19,634 --> 00:00:20,667 IT'S WHEN THEY GET OUT OF 12 00:00:20,667 --> 00:00:22,400 BALANCE THAT THINGS HAPPEN. 13 00:00:22,400 --> 00:00:23,934 READY? 14 00:00:23,934 --> 00:00:25,033 GRAVITY IS THE FORCE OF 15 00:00:25,033 --> 00:00:26,934 ATTRACTION BETWEEN THINGS. 16 00:00:26,934 --> 00:00:29,167 IT'S WHAT MAKES THINGS FALL. 17 00:00:29,167 --> 00:00:32,667 (SCREAMING) 18 00:00:32,667 --> 00:00:33,567 THERE ARE THREE LAWS 19 00:00:33,567 --> 00:00:34,667 OF MOTION DISCOVERED BY SIR 20 00:00:34,667 --> 00:00:36,167 ISAAC NEWTON. 21 00:00:36,167 --> 00:00:38,133 AN OBJECT THAT ISN'T BEING 22 00:00:38,133 --> 00:00:40,868 PUSHED OR PULLED BY A FORCE 23 00:00:40,868 --> 00:00:43,000 EITHER STAYS STILL OR KEEPS 24 00:00:43,000 --> 00:00:44,334 MOVING IN A STRAIGHT LINE AT A 25 00:00:44,334 --> 00:00:47,300 CONSTANT SPEED. 26 00:00:47,300 --> 00:00:51,901 (SCREAMING) 27 00:00:51,901 --> 00:00:52,801 STUDENT: WAIT A 28 00:00:52,801 --> 00:00:54,167 MINUTE, GRAVITY PULLED ME DOWN 29 00:00:54,167 --> 00:00:55,267 IN A STRAIGHT LINE. 30 00:00:55,267 --> 00:00:56,767 WHY DID WE STOP? 31 00:00:56,767 --> 00:00:58,033 CARTAN-HANSEN: WELL, NEWTON'S 32 00:00:58,033 --> 00:01:00,267 FIRST LAW IS ALL ABOUT INERTIA. 33 00:01:00,267 --> 00:01:01,467 INERTIA IS AN OBJECT'S TENDENCY 34 00:01:01,467 --> 00:01:02,934 TO RESIST ANY CHANGE IN ITS 35 00:01:02,934 --> 00:01:05,367 MOTION. 36 00:01:05,367 --> 00:01:07,501 A BODY AT REST STAYS AT REST. 37 00:01:07,501 --> 00:01:08,634 A BODY IN MOTION STAYS IN 38 00:01:08,634 --> 00:01:11,100 MOTION. 39 00:01:11,100 --> 00:01:12,400 IF GRAVITY WAS THE ONLY FORCE, 40 00:01:12,400 --> 00:01:14,701 YOU'D JUST KEEP SLIDING. 41 00:01:14,701 --> 00:01:16,267 ANOTHER FORCE CALLED "FRICTION" 42 00:01:16,267 --> 00:01:20,501 SLOWS YOU DOWN, AND YOU STOP. 43 00:01:20,501 --> 00:01:22,767 FORCES MAKE THINGS MOVE. 44 00:01:22,767 --> 00:01:24,167 THE BIGGER THE FORCE OR THE 45 00:01:24,167 --> 00:01:26,133 LIGHTER THE OBJECT, THE GREATER 46 00:01:26,133 --> 00:01:28,534 THE MOTION. 47 00:01:28,534 --> 00:01:29,767 SAY YOU PUSH A TOY ALONG THE 48 00:01:29,767 --> 00:01:31,267 STREET, IT'S PRETTY EASY BECAUSE 49 00:01:31,267 --> 00:01:32,501 THE TOY IS LIGHT, AND YOU CAN 50 00:01:32,501 --> 00:01:34,067 PUSH OR PULL WITH A LOT OF 51 00:01:34,067 --> 00:01:35,534 FORCE. 52 00:01:35,534 --> 00:01:36,767 THE MORE FORCE, THE FASTER IT 53 00:01:36,767 --> 00:01:39,534 MOVES OR ACCELERATES. 54 00:01:39,534 --> 00:01:41,901 STUDENT: GOOD AIM! 55 00:01:41,901 --> 00:01:43,200 CARTAN-HANSEN: SAY YOU TRY TO 56 00:01:43,200 --> 00:01:44,567 PUSH OR PULL SOMETHING REALLY 57 00:01:44,567 --> 00:01:45,701 BIG, IT WOULD TAKE A LOT OF 58 00:01:45,701 --> 00:01:48,267 FORCE TO GET IT TO MOVE. 59 00:01:48,267 --> 00:01:50,200 EVERY ACTION HAS AN EQUAL AND 60 00:01:50,200 --> 00:01:54,567 OPPOSITE REACTION. 61 00:01:54,567 --> 00:01:56,467 FORCES ACT IN PAIRS. 62 00:01:56,467 --> 00:01:57,801 WHEN THE SPACE SHUTTLE LIFTS 63 00:01:57,801 --> 00:01:59,334 OFF, THE BURNING GAS PUSHES OUT 64 00:01:59,334 --> 00:02:00,634 THE ENGINE AND LIFTS THE 65 00:02:00,634 --> 00:02:02,367 SHUTTLE. 66 00:02:02,367 --> 00:02:04,067 WHEN YOU HIT YOUR FRIEND WITH A 67 00:02:04,067 --> 00:02:05,234 BUMPER CAR, THE FORCE PUSHES HIM 68 00:02:05,234 --> 00:02:06,667 AWAY, BUT THE FORCE OF HIS CAR 69 00:02:06,667 --> 00:02:08,734 PUSHES YOU BACK THE SAME AMOUNT 70 00:02:08,734 --> 00:02:11,000 OF FORCE. 71 00:02:11,000 --> 00:02:12,234 HIT HIM SOFTLY, YOU BOTH MOVE 72 00:02:12,234 --> 00:02:13,968 JUST A LITTLE. 73 00:02:13,968 --> 00:02:16,534 HIT HIM HARD, WOO-HOO, EQUAL AND 74 00:02:16,534 --> 00:02:19,234 OPPOSITE REACTION. 75 00:02:19,234 --> 00:02:20,367 THE LAWS OF MOTION ARE THE BASIS 76 00:02:20,367 --> 00:02:24,100 FOR THE SCIENCE OF PHYSICS. 77 00:02:24,100 --> 00:02:25,300 THEY APPLY TO ALL THE PARTICLES 78 00:02:25,300 --> 00:02:26,834 IN THE UNIVERSE FROM THE 79 00:02:26,834 --> 00:02:27,934 SMALLEST ATOM TO EVEN THE 80 00:02:27,934 --> 00:02:30,234 BIGGEST PLANETS. 81 00:02:30,234 --> 00:02:32,901 EVEN THIS ROLLER COASTER. 82 00:02:33,734 --> 00:02:34,734 STUDENT: STAY AT REST UNTIL 83 00:02:34,734 --> 00:02:36,534 ACTED ON BY AN OUTSIDE FORCE; 84 00:02:36,534 --> 00:02:38,234 THAT'S NEWTON'S FIRST LAW. 85 00:02:38,234 --> 00:02:39,734 AND WHEN AN ENGINE PULLS THE 86 00:02:39,734 --> 00:02:41,334 CARS UP THE HILL, THAT'S 87 00:02:41,334 --> 00:02:43,501 NEWTON'S SECOND LAW. 88 00:02:43,501 --> 00:02:44,868 APPLYING A FORCE MAKES AN OBJECT 89 00:02:44,868 --> 00:02:46,300 MOVE. 90 00:02:46,300 --> 00:02:47,467 AND HOW DOES THE THIRD LAW 91 00:02:47,467 --> 00:02:48,767 APPLY? 92 00:02:48,767 --> 00:02:49,767 CARTAN-HANSEN: AND FOR EVERY 93 00:02:49,767 --> 00:02:51,100 ACTION THERE'S AN EQUAL AND 94 00:02:51,100 --> 00:02:52,133 OPPOSITE REACTION. 95 00:02:52,133 --> 00:02:58,100 FIRST WE GO UP, THEN WE GO DOWN.