00:01
A blue pebble is dropped from h1 and has a mass of m1.
00:05
A red pebble is dropped from twice the height of the blue pebble and has a mass of m2.
00:13
If they both hit the floor at the same kinetic energy, how do their masses compare? to answer this question we need two equations.
00:20
The first is that potential energy is equal to kinetic energy.
00:25
The equation for potential energy is mass times the gravitational constant g times the height.
00:34
So we're going to start with the blue pebble first.
00:37
And we're going to translate its kinetic energy to potential energy.
00:41
And we're going to say the potential energy of the blue pebble is going to equal the potential energy of the red pebble.
00:49
And this is because they have the same kinetic energies.
00:52
So therefore the mass of the red pebble times the gravitational constant times its height has to equal the mass of the blue pebble times its gravitational constant times its height.
01:08
So immediately we can see that the g's are on both sides so that they can cancel out.
01:13
So we are going to rewrite this as m1 times its height is equal to m2 times its height.
01:22
Or twice that of h1...