00:01
A 62 kilogram trampoline artist jumps upwards from the top of a platform with a vertical speed of 4 .5 meters per second.
00:08
How fast are they going if they leaned on the trampoline 2 meters below? okay, so for part a, let's use conservation of energy.
00:20
So 1 half m v1 squared plus mgy1 is equal to 1 1 .5m, the velocity at 2 squared, plus m g, y2.
00:38
Okay, so we know that v1 is 4 .5 meters per second.
00:52
We know y1 is equal to 2 meters.
00:58
Y2 is equal to 0 meters.
01:02
So filling in these values and solving for v2, v2 is equal to 7 .7 meters per second.
01:16
Part b, if the trampoline behaves like a spring of spring constant, 5 .8 times 10 to the 4th newtons per meter, how far do they depress it? okay, so again, conservation of energy, and this time it's a spring, so we have 1 .5m v2 squared plus m g y2 and then plus spring potential energy, which is 1 .5k .y2 squared equals 1 .5m v3 squared plus the potential energy.
01:54
So kinetic potential spring plus 1 .5ky2 squared...