00:01
Okay, question 9 .1.
00:02
If a particle of mass m that has momentum p, we want to show that the kinetic energy of the particle is p squared over 2m.
00:11
Let's just remind ourselves what kinetic energy is.
00:15
It's 1 1 half m v squared, and momentum is just m times v.
00:21
So let's solve that second equation for v.
00:26
So v is equal to p over m, because we want our kinetic energy to be just in terms of p.
00:35
P and m.
00:36
So if we can get rid of the v, we'll be good to go.
00:40
I'll take that v and plug it into our kinetic energy equation.
00:45
So we get, this is part a, by the way, so we get k equals 1 half m and then times v squared, well what's v? it's p over m, p over m and that's squared...