# Collision help

1. Jan 22, 2008

### dboychuk

In a physics lab, a small cube slides down a frictionless incline as shown, and collides at the bottom (where it is now moving horizontally) with a cube that is only one-half its mass. If the incline is 30 CM high and the table is 90 CM off the floor. where does each cube land?

the teacher gave us that the big cube lands 30 CM away. Thats all, does anyone know how to solve this?

2. Jan 23, 2008

### physixguru

calculate the velocity of cube at bottom of incline with the relation...

v=[2gh]^1/2

apply momentum conservation principle after that..
both k.e. and p.e. will come into play....

tell me if ya are still not able to solve it..

3. Jan 23, 2008

### physixguru

A:v of small cube=4.8m/s using v=[2gh]^1/2 [here, the incline is not useful at all ;except for calculating speed of cube]

where h = 90+30= 120cm>>1.2 m;[height from ground is taken into consideration]

M AND M/2;

After collision the small cube comes to rest.

M/2*4.8=M*V>>V=2.4m/s [MOMENTUM CONSERVATION][inelastic collision]

>>V^2 =U^2 +2AS
>>s = 30 cm