Question

A small ball of mass m is aligned above a larger ball of mass M = 0.63kg (with a slight separation) and the two are dropped simultaneously from a height of 1.8m. If the larger ball rebounds elastically from the floor and the small ball rebounds elastically from the larger ball what value of m results in the larger ball stopping when it collides with the small ball?

Answer 1

 a) M is the big one 
m is the little one 

v is the speed of each of them when they impact 

V = speed of mii after collision 

Conservation of momentum 

Mv – mv = mV 

Conservation of energy 

1/2Mv^2 + 1/2mv^2 = 1/2 mV^2 

This pair simplify to give 

M = 3m 

V = 2v 

So m = 0.21kg 

and h = 4 . 2.7 = 10.8 mSource(s):Old teacher