About elastic collision

[weizhi li]

Homework Statement

a uranium atom traveling at speed 4 *

m/s collides elastically with astationary hydrogen molcule. head on. what is the approximate finalspeed of the hydrogen molecule?

Homework Equations

The answer is about 8*10^4 m/s

But, i tried many times and failed.

The Attempt at a Solution

MY thought is that the speed of uranium atom after collision should be the same but in different direction, which means the momentum of hydrogen after collision is 2*p1(p1 is uranium momentum before collision). and use this to calculate the speed by plugging into the formula k = p^2 / 2m

 

[gneill]

The problem is an exercise in elastic collision. Your relevant equations should include formulas that pertain to elastic collisions. In particular, the conservation laws that are applicable. You also need to look up the relative masses of the particles in question.