# Momentum questions

1. Jun 13, 2013

### Fresko

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

2. Relevant equations

Mg deltha H

1/2mv^2

p=mv

3. The attempt at a solution

I believe statement to do with the Gravitational energy is correct, considering the equation I listed. I would have to agree with statement 2 since gpe=ke

Here is what I am thinking, I disagree with the Ke = the same as before collision.

my reason is 1/2mv^2= 0.16j ----- v= sqrt (0.32/71.6ex-3) now if this is correct we can work out the momentum

which i have down as 1.5 x10^-1 using, momentum is conserved we can work out velocity of the pellet which turns out to be 180m/s (I think this could be wrong)

But could I just say that, the collision was inelastic, hence kinetic energy is not conserved, therefore working out velocity from Momentum would be better since momentum is conserved.

Last edited: Jun 13, 2013
2. Jun 13, 2013

### Staff: Mentor

This is a terribly formatted post can you clean it up a bit and make sure your equations are correct and readable?

3. Jun 13, 2013

### Fresko

done

4. Jun 13, 2013

### Fresko

anyone help?

5. Jun 13, 2013

### haruspex

6. Jun 14, 2013

### Fresko

Are you being serious or troll? I can't tell

If you could outline what is actually good and makes sense in my answer would make me more confident.

7. Jun 14, 2013

### Staff: Mentor

haruspex is most definetly not a troll -- he is one of our very valued Homework Helpers and Science Advisors.

8. Jun 14, 2013

### haruspex

I was being quite serious . You correctly identified the flaw in the student's reasoning, and that the correct way is to use conservation of momentum.

9. Jun 14, 2013

### Fresko

but doesn't 180m/s seem to big of a value for the velocity.

10. Jun 14, 2013

### haruspex

No, it looks right to me. Remember that the pellet is only 1/90 of the mass of the ball.