# Thread: Physics Energy and Momemtum

1. ## Physics Energy and Momemtum

A 10.5 kg block, attached to the left end of a horizontal massless spring, sits on a frictionless table. The right end of the spring is attached to a vertical piece of wood that is firmly nailed to the table. A 0.0500 kg projectile is fired, from left to right, into the block at 85.5 m/s and stops inside it (this is a completely inelastic collision). The spring constant is k = 105 N/m. How many meters does the spring compress? The potential energy due to the compression of the spring can be calculated with the following formula: PE = (1/2)kx^2

2. oops >_> just realized I posted in the wrong section...i swear i posted in the urgent hw >_> how did it end up here @_@

3. Originally Posted by Linnus
A 10.5 kg block, attached to the left end of a horizontal massless spring, sits on a frictionless table. The right end of the spring is attached to a vertical piece of wood that is firmly nailed to the table. A 0.0500 kg projectile is fired, from left to right, into the block at 85.5 m/s and stops inside it (this is a completely inelastic collision). The spring constant is k = 105 N/m. How many meters does the spring compress? The potential energy due to the compression of the spring can be calculated with the following formula: PE = (1/2)kx^2
I don't have much time so I'll just run through the procedure.

Use conservation of momentum to find the speed of the block/bullet after the collision.

Then use conservation of energy to find out how much the spring compresses.

-Dan