00:01
Okay for this question we have a basketball dropped out of a window that's 6 .3 meters above the ground.
00:07
The ball is caught by a person whose hands are 1 .81 meters above the ground.
00:13
A.
00:13
How much work done by the ball by its weight? what's the gravitational potential energy of the basketball relative to the ground? when it's b.
00:24
Release.
00:24
Okay let's focus on a first then.
00:27
So the weight of the basketball, a .k.
00:32
Is...
00:33
So the work done by its weight is force times distance.
00:38
So it's m .g.
00:39
Times distance relative to the ground.
00:42
So it's 0 .568 kg times 9 .81 times by the distance which is 4 .49 meters because it's caught 1 .81 meters above the ground which comes out to 25 joules of energy.
01:05
Okay so for b.
01:06
What is the gravitational potential energy relative to the ground when it's released? so potential energy is equal to m .g .h.
01:18
When it's released h is 6 .3 meters because it's relative to the ground.
01:22
So that would be 0 .568 times 9 .81 times 6 .3 which is 35 joules of energy.
01:35
Okay.
01:38
C.
01:38
When it's caught.
01:40
That would be the same it's just h is equal to 4.
01:47
When it's caught h would be 1 .81 meters because that's the height it's caught at.
01:52
So potential energy would be 0 .586 times 9 .81 times 1 .81 meters which is about 10 joules.
02:03
Okay.
02:04
And then for d.
02:07
What's the change in potential energy of the...
02:10
What is the change in the ball's gravitational potential energy? okay.
02:17
And so the change in potential energy is equal to m .g...