1
00:00:00,834 --> 00:00:15,281
[ MUSIC ]

2
00:00:24,891 --> 00:00:25,525
>> HELLO, MY NAME

3
00:00:25,592 --> 00:00:26,359
IS SHANE KIMBROUGH,

4
00:00:26,426 --> 00:00:27,227
AND I'M AN ASTRONAUT

5
00:00:27,293 --> 00:00:28,528
LIVING AND WORKING ABOARD

6
00:00:28,595 --> 00:00:30,530
THE INTERNATIONAL SPACE STATION.

7
00:00:30,597 --> 00:00:31,464
WE'RE CURRENTLY ORBITING

8
00:00:31,531 --> 00:00:32,632
250 MILES ABOVE

9
00:00:32,699 --> 00:00:33,666
THE EARTH'S SURFACE

10
00:00:33,733 --> 00:00:34,434
AT APPROXIMATELY

11
00:00:34,501 --> 00:00:37,404
17,500 MILES PER HOUR.

12
00:00:37,470 --> 00:00:38,071
YOU MAY BE WONDERING

13
00:00:38,138 --> 00:00:38,772
HOW IT'S POSSIBLE

14
00:00:38,838 --> 00:00:39,806
FOR THE SPACE STATION TO BE

15
00:00:39,873 --> 00:00:41,775
CONTINUOUSLY ORBITING EARTH.

16
00:00:41,841 --> 00:00:42,575
WELL, TODAY, WE'RE GOING TO

17
00:00:42,642 --> 00:00:43,643
ANSWER THAT QUESTION

18
00:00:43,710 --> 00:00:45,545
AND EXPLORE CENTRIPETAL FORCE

19
00:00:45,612 --> 00:00:46,946
IN THE MICROGRAVITY ENVIRONMENT

20
00:00:47,013 --> 00:00:48,715
OF THE SPACE STATION.

21
00:00:48,782 --> 00:00:51,317
LET'S GET STARTED.

22
00:00:51,384 --> 00:00:52,252
BEFORE WE DIVE INTO

23
00:00:52,318 --> 00:00:53,386
CENTRIPETAL FORCE,

24
00:00:53,453 --> 00:00:54,220
IT'S IMPORTANT TO LOOK

25
00:00:54,287 --> 00:00:56,289
AT NEWTON'S FIRST LAW OF MOTION,

26
00:00:56,356 --> 00:00:57,424
WHICH STATES THAT AN OBJECT

27
00:00:57,490 --> 00:00:58,458
WILL CONTINUE MOVING

28
00:00:58,525 --> 00:01:00,093
WITH A CONSTANT VELOCITY

29
00:01:00,160 --> 00:01:01,428
ALONG A STRAIGHT PATH

30
00:01:01,494 --> 00:01:02,595
UNLESS ACTED UPON

31
00:01:02,662 --> 00:01:04,931
BY A NET EXTERNAL FORCE.

32
00:01:04,998 --> 00:01:05,365
THIS MEANS THAT

33
00:01:05,432 --> 00:01:06,466
THE SPACE STATION WILL

34
00:01:06,533 --> 00:01:07,901
MOVE ALONG A STRAIGHT PATH

35
00:01:07,967 --> 00:01:09,269
IF IT WEREN'T FOR ONE KEY

36
00:01:09,335 --> 00:01:11,404
EXTERNAL FORCE ACTING ON IT--

37
00:01:11,471 --> 00:01:13,873
EARTH'S GRAVITATIONAL PULL.

38
00:01:13,940 --> 00:01:14,307
ANOTHER NAME

39
00:01:14,374 --> 00:01:15,909
FOR THIS EXTERNAL FORCE

40
00:01:15,975 --> 00:01:17,944
IS CENTRIPETAL FORCE.

41
00:01:18,011 --> 00:01:18,978
A CENTRIPETAL FORCE

42
00:01:19,045 --> 00:01:19,946
IS ANY NET FORCE

43
00:01:20,013 --> 00:01:21,247
THAT KEEPS AN OBJECT MOVING

44
00:01:21,314 --> 00:01:22,916
ALONG A CIRCULAR PATH.

45
00:01:22,982 --> 00:01:24,083
GRAVITY, IN THIS CASE,

46
00:01:24,150 --> 00:01:25,852
IS A CENTRIPETAL FORCE

47
00:01:25,919 --> 00:01:26,820
BECAUSE IT IS THE FORCE

48
00:01:26,886 --> 00:01:27,654
THAT IS KEEPING

49
00:01:27,720 --> 00:01:28,922
OUR SPACE STATION MOVING

50
00:01:28,988 --> 00:01:30,156
IN ITS CIRCULAR PATH

51
00:01:30,223 --> 00:01:32,992
AROUND EARTH.

52
00:01:33,059 --> 00:01:34,194
ALL RIGHT, HERE'S OUR EXAMPLE.

53
00:01:34,260 --> 00:01:35,695
WE HAVE AKI HERE THAT HAS

54
00:01:35,762 --> 00:01:37,397
AN OBJECT TIED TO A STRING.

55
00:01:37,464 --> 00:01:38,364
IT'S JUST A YO-YO,

56
00:01:38,431 --> 00:01:39,132
BUT IT'S AN OBJECT

57
00:01:39,199 --> 00:01:40,733
ON THE END OF A STRING.

58
00:01:40,800 --> 00:01:41,334
HE'S GONNA WHIRL

59
00:01:41,401 --> 00:01:42,802
THIS OBJECT AROUND,

60
00:01:42,869 --> 00:01:43,703
ATTACHED TO THE STRING

61
00:01:43,770 --> 00:01:44,304
SO THAT IT'S MOVING

62
00:01:44,370 --> 00:01:46,973
IN A CIRCULAR PATH.

63
00:01:47,040 --> 00:01:48,107
THE STRING IN THIS DEMONSTRATION

64
00:01:48,174 --> 00:01:49,642
PROVIDES A FORCE OF TENSION

65
00:01:49,709 --> 00:01:51,711
WHICH IS THE CENTRIPETAL FORCE

66
00:01:51,778 --> 00:01:53,680
KEEPING THE YO-YO REVOLVING

67
00:01:53,746 --> 00:01:56,983
AROUND AKI'S HAND.

68
00:01:57,050 --> 00:01:57,884
IT'S IMPORTANT TO NOTE

69
00:01:57,951 --> 00:01:58,985
THAT CENTRIPETAL MEANS

70
00:01:59,052 --> 00:02:00,086
"CENTER SEEKING."

71
00:02:00,153 --> 00:02:02,255
THEREFORE A CENTRIPETAL FORCE

72
00:02:02,322 --> 00:02:04,991
IS A CENTER-SEEKING FORCE.

73
00:02:05,058 --> 00:02:06,459
CENTRIPETAL FORCE IS ALWAYS

74
00:02:06,526 --> 00:02:07,994
DIRECTED INWARD,

75
00:02:08,061 --> 00:02:08,895
TOWARD THE CENTER

76
00:02:08,962 --> 00:02:10,930
OR AXIS OF REVOLUTION.

77
00:02:10,997 --> 00:02:11,831
THIS IS BECAUSE IT'S

78
00:02:11,898 --> 00:02:12,966
THE FORCE OF TENSION

79
00:02:13,032 --> 00:02:14,501
FROM THE STRING PULLING INWARD

80
00:02:14,567 --> 00:02:15,635
THAT KEEPS THE YO-YO

81
00:02:15,702 --> 00:02:16,769
REVOLVING AROUND

82
00:02:16,836 --> 00:02:18,771
THE AXIS OF REVOLUTION.

83
00:02:18,838 --> 00:02:19,739
NOW AKI'S GOING TO SET

84
00:02:19,806 --> 00:02:20,707
THE OBJECT MOVING

85
00:02:20,773 --> 00:02:22,809
IN A CIRCULAR PATH FREE

86
00:02:22,876 --> 00:02:24,043
AND REMOVE THAT CENTRIPETAL

87
00:02:24,110 --> 00:02:26,379
FORCE BY RELEASING THE STRING.

88
00:02:26,446 --> 00:02:27,213
AS YOU SAW,

89
00:02:27,280 --> 00:02:28,481
ONCE THE TENSION FROM THE STRING

90
00:02:28,548 --> 00:02:29,349
OR CENTRIPETAL FORCE

91
00:02:29,415 --> 00:02:30,316
WAS REMOVED...

92
00:02:30,383 --> 00:02:30,884
>> SLOW-MO VIEW.

93
00:02:30,950 --> 00:02:31,718
>> THE OBJECT CONTINUES

94
00:02:31,784 --> 00:02:32,619
TO FOLLOW NEWTON'S

95
00:02:32,685 --> 00:02:34,554
FIRST LAW OF MOTION.

96
00:02:34,621 --> 00:02:35,221
IT KEEPS MOVING

97
00:02:35,288 --> 00:02:36,856
AT A CONSTANT VELOCITY

98
00:02:36,923 --> 00:02:38,124
ALONG A STRAIGHT PATH

99
00:02:38,191 --> 00:02:41,160
RELATIVE TO THE SPACE STATION.

100
00:02:41,227 --> 00:02:42,562
CAN YOU THINK OF OTHER EXAMPLES

101
00:02:42,629 --> 00:02:43,663
OF CENTRIPETAL FORCES

102
00:02:43,730 --> 00:02:45,164
BACK ON EARTH?

103
00:02:45,231 --> 00:02:45,698
TO LEARN MORE

104
00:02:45,765 --> 00:02:46,900
ABOUT CENTRIPETAL FORCE,

105
00:02:46,966 --> 00:02:47,901
USE THE CORRESPONDING

106
00:02:47,967 --> 00:02:49,602
CLASSROOM CONNECTION

107
00:02:49,669 --> 00:02:51,538
TO CONDUCT YOUR OWN EXPERIMENTS

108
00:02:51,604 --> 00:02:52,839
AND DISCOVER OTHER WAYS

109
00:02:52,906 --> 00:02:54,707
CENTRIPETAL FORCES PLAY OUT

110
00:02:54,774 --> 00:02:56,543
IN YOUR EVERYDAY LIFE.

111
00:02:56,609 --> 00:02:57,443
THANKS FOR EXPLORING

112
00:02:57,510 --> 00:02:58,945
SOME PHYSICS WITH ME TODAY.

113
00:02:59,012 --> 00:03:00,747
SEE YOU AGAIN SOON.