00:01
Okay, we have a .5 kilogram ball, and it rolls down the ramp into a circular loop.
00:09
And when it's at the top of the loop, i believe, it has a height of 30 centimeters, or 2r, and a velocity of 3 .43 meters per second.
00:29
So we want to figure out how high did the ball start at.
00:35
So what's that height h? so i've drawn it when the balls at the top of the loop, but let me also draw the ball up here.
00:46
So we're going to label this initial, i for initial, and over here it would be f for final.
00:57
So what we're going to do here is use conservation of energy which tells us, in the absence of friction, the initial energy in our system will be equal to the final energy in our system.
01:10
We want to pick a place where gravitational potential energy is zero.
01:17
Let's do at ground level.
01:22
So what's our initial energy? mgh.
01:26
It's not moving because we're told it moves from rest.
01:32
So it starts at the top of the hill from rest, so all it has is potential energy.
01:36
It rolls down the hill.
01:37
Whatever, it doesn't roll actually because there's no friction.
01:42
It just slides...