1
00:00:00,360 --> 00:00:08,070
‫Finally, let's take one more example, and that will be your exercise again, you have the same bowl

2
00:00:08,430 --> 00:00:16,740
‫and you have the same force that points at an angle of 30 degrees like this.

3
00:00:17,280 --> 00:00:21,630
‫And the magnitude of the force vector is five Newtons.

4
00:00:22,110 --> 00:00:30,810
‫However, now we will add one more force that points down, and it's the force of gravity and the force

5
00:00:30,810 --> 00:00:36,140
‫of gravity is equal to the vertical component of this applied force.

6
00:00:36,750 --> 00:00:46,680
‫So the vertical component of this applied force would be the force vector magnitude times sine thirty

7
00:00:46,680 --> 00:00:47,310
‫degrees.

8
00:00:47,910 --> 00:00:54,390
‫And that means that the gravity force is minus five times sine thirty degrees.

9
00:00:54,870 --> 00:00:59,370
‫Because this thing here, don't forget it's five Newtons.

10
00:00:59,910 --> 00:01:07,110
‫And of course this applied force also has a horizontal component, which is this one, and it's the

11
00:01:07,110 --> 00:01:10,500
‫magnitude of the force times cosine.

12
00:01:10,500 --> 00:01:11,510
‫Thirty degrees.

13
00:01:11,820 --> 00:01:13,380
‫So five times cosine.

14
00:01:13,380 --> 00:01:14,270
‫Thirty degrees.

15
00:01:14,970 --> 00:01:23,280
‫So you have two forces here, this one the Applied Force and you have the gravity force that points

16
00:01:23,730 --> 00:01:29,340
‫down, which is equal to the vertical component of the applied force.

17
00:01:29,880 --> 00:01:36,620
‫And now your job is to compute the total work done in this system.

18
00:01:37,170 --> 00:01:39,360
‫What's the total work in the system?

19
00:01:39,960 --> 00:01:44,700
‫And of course, in order to compute the work, you need to know how the ball has moved.

20
00:01:44,880 --> 00:01:55,470
‫So the ball has moved from here to here, a horizontal distance and the distance that it has moved is

21
00:01:56,040 --> 00:01:59,700
‫20 times cosine, 30 degrees meters.

22
00:02:00,090 --> 00:02:06,780
‫But it makes sense that the ball has only moved horizontally because the vertical forces there are equal,

23
00:02:07,230 --> 00:02:09,720
‫but they are in the opposite direction.

24
00:02:10,080 --> 00:02:15,570
‫So the gravity force is cancelled by the vertical component of the applied force.

25
00:02:15,960 --> 00:02:23,370
‫So there is no way that this floating ball can move in a vertical direction.

26
00:02:23,520 --> 00:02:24,750
‫It can't go up.

27
00:02:24,750 --> 00:02:26,040
‫It can go down.

28
00:02:26,340 --> 00:02:33,990
‫However, the horizontal component of the supplied force will move the ball from this point to this

29
00:02:33,990 --> 00:02:39,180
‫point, and the distance is 20 times cosine, 30 degrees meters.

30
00:02:39,510 --> 00:02:44,650
‫So with that in mind, try to compute the total work in this system.

31
00:02:45,060 --> 00:02:46,260
‫See you in the next video.