# Homework Help: Momentum question help

1. Nov 9, 2015

### SuchBants

1. The problem statement, all variables and given/known data
V of Alpha at T1 = 10^7
V of Alpha at T2 = 0.6 x 10^7
Mass of Alpha = 4x mass of proton

2. Relevant equations
P=MV
P1 = P2

3. The attempt at a solution
Bear in mind that I am a year 11 IGCSE student. This is from the textbook at the end of the chapter of forces and motion detailing simple momentum and speed equations.
I've tried many solutions that produce varied results for me.

2. Nov 9, 2015

### Staff: Mentor

Can you show us what you have obtained and explain why you think it is incorrect?

3. Nov 9, 2015

### SuchBants

I could only ever get as far as arranging the equation using the principle that Momentum before = momentum after. But as I have no values for the masses I found I could not rearrange.
p1= 4m x 107
P2= (4m x107x0.6) + (m x V)
P1 = P2

As you can see I'm stumped here.

4. Nov 9, 2015

### Staff: Mentor

You just need to continue. In that last equation, substitute P1 and P2 using the other equalities you have, and try and find and equation for V.

5. Nov 9, 2015

### SuchBants

But surely it would be impossible to get a value for V ? Given that we don't know the mass of m or 4m.

6. Nov 9, 2015

### Staff: Mentor

Write out the equations and see what happens.

7. Nov 14, 2015