# Homework Help: Conservation of momentum and energy

1. Oct 9, 2009

### karis

1. The problem statement, all variables and given/known data

A nucleus originally at rest splits into two fragments of unequal mass. The fragment with smaller mass has a larger
1.momentum
2.speed
3.Kinetic energy

A. 1only
B. 3only
C. 1&2 only
D. 2&3 only
E. 1,2 &3
3. The attempt at a solution
well, i can figure out the speed of the smaller mass will be larger, but how about the momentum and the kinetic energy?
in what way can i determine if they will be larger or not?

The ans is D
Thank You=)

2. Oct 9, 2009

### rl.bhat

Hi karis, wecome to PF.

Since originally the nucleus is at rest, after splitting two fragments must have equal and opposite momentum, irrespective of their unequal masses.
Hence smaller mass must have...........speed.
The relation between momentum and kinetic energy can be written as
p = sqrt(2mE) where E is KE.
Since p is the same for both the fragments,
smaller mass will have .......KE.

3. Oct 9, 2009

### karis

Thank you very much:)