Conservation of Linear Momentum Problem (Need help)

[Kaleem]

Homework Statement

A 4.60-kg ball, moving to the right at a velocity of +2.31 m/s on a frictionless table, collides head-on with a stationary 9.80-kg ball. Find the final velocities of (a) the 4.60-kg ball and of (b) the 9.80-kg ball if the collision is elastic. (c) Find the magnitude and direction of the final velocity of the two balls if the collision is completely inelastic.

Homework Equations

P = (mv_f1+mv_f2) - (mv_i1+mv_i2)

The Attempt at a Solution

I understand part c since they will have a combined mass and the same final velocity and that Vi₂=0 however i can't figure out how to solve parts A and B.

 

[BruceW]

hi, welcome to physicsforums :)
For part a) and b) you are meant to assume the collision is elastic. So what kind of condition is this? and can you use this to find an answer to the problem?

 

[Kaleem]

hi, welcome to physicsforums :)
For part a) and b) you are meant to assume the collision is elastic. So what kind of condition is this? and can you use this to find an answer to the problem?

Since the collision is elastic would it be safe to assume that kinetic energy is conserved?

 

[BruceW]

yes! and what else is conserved in the collision?

 

[Kaleem]

yes! and what else is conserved in the collision?

I'm not exactly sure, is it mechanical energy?

 

[BruceW]

there are not potential energies here. Think of something else that is conserved in collision. (hint: it is conserved in inelastic collisions too).

 

[Satvik Pandey]

As there is a elastic collision so you can use that ($e$(coefficient of restitution)=1). So velocity of separation is equal to the velocity of approach in common normal direction. This will give you a relation between the velocities of the balls. You have mentioned a name of a concept in the title of this thread. Just use that concept.