Question

I need some help with an AP Physics problem.

I have a .025 kg block moving at .2 m/s and it hits a .01 kg block moving .15 m/s, I need to find the resulting velocity of each block. @Mathematics

Answer 1

at what angle do they hit?

Answer 2

This is a momentum question?

Answer 3

Yes, this is a momentum question. They are in a straight line going in the same direction.

Answer 4

This is the actual problem word for word if it helps.

A 25.0-g object moving to the right at 20.0 cm/s overtakes and collides elastically with a 15.0-g object moving the in same direction at 15.0 cm/s. Find the velocity of each object after the collision.

Answer 5

p = mv always.

I think,

p1 = 0.005 kg m/s
p2 = 0.0015 kgm/s

When p1 and p2 collide

m1u1 + m2u2 = m1v1 + m2v2
(0.025)(0.2) + (0.01)(0.15) = (0.025)(v1) + (0.01)(v2)

That is as far as I can go. There probably is some piece of information missing.

Answer 6

But if the collision is perfectly inelastic,

then v1 = v2

and you solve for v,

v = [6.5 X 10^-3] / (0.025 + 0.01)
= 0.185 m/s

Answer 7

The answer 17.1 cm/s for the 25 g object and 22.1 cm/s for 10 g gram object. I'm going to try and work backwards and figure something out. Thank you for your effort.

Answer 8

that is the same as 18.5 cm/s

Answer 9

I'm going to try to work with the equations and substitute. Maybe something will work out.

Answer 10

Very well. Good luck.

Answer 11

Helpful hint... momentum AND kinetic energy are conserved. So maybe try and find a way to relate the two equations:
\[p=mv\]\[KE=(1/2)mv{^2}\]
Keeping in mind the 'initial' and 'final' should balance.

Answer 12

This may help you see the steps...problem #37 is almost exactly the same:

http://physics.ucsd.edu/students/courses/summer2009/session1/managed/session1/physics1a/documents/Ch6_solutions.pdf