physic equation needed?

Question

A 4.00-g bullet is fired with a velocity of 96 m/s toward a 10.00-kg stationary solid block resting on a frictionless surface.

(a) What is the change in momentum of the bullet if it is embedded in the block?
kg·m/s
(b) What is the change in momentum of the bullet if it ricochets in the opposite direction with a speed of 95 m/s-almost the same speed as it had originally?
kg·m/s

Answer 1

p = m v
where p is the momentum, m is the mass and v is the velocity (a vector).

They give you the mass and velocity. So, finding the initial momentum is easy with this formula. To find the final momentum of the bullet you need to use conservation of momentum. Since momentum is conserved the combined momentum of the block and the bullet must equal the initial momentum of the bullet. You can use the same formula to find the velocity of the bullet and block. Then use the velocity and mass of the bullet to find the final momentum of the bullet. Subtract the initial momentum from the final to get the change in momentum.

b is even easier. use the same formula as above to get the final momentum of the bullet. Subtract the initial momentum from the final momentum to get the change in momentum