# Momentum/SHM problems

1. Jan 7, 2008

### getupforletdo

1. The problem statement, all variables and given/known data
a massless spring is between a 1-kg and 3-kg mass as shown.but it is not attached to either mass. Both masses are on a horizontal frictionless table. In an experiment, the 1 kg mass is held in place and the spring is compressed by pushing the 3 kg mass. the 3 kg mass is then released and moves off wiht a speed of 10 m/s.

a. determine the minimum work needed to compress the spring in this experiment.

b. the spring is compressed again exactly as above. but this time both masses are released simultaneously. determine the final velocity of each mass relative to teh table after the masses are released.

i've found a. by using work done=change in kinetic energy and got 150 joules.

B. i have no real idea how to start this problem, i think that the amount of work may stay the same but im not sure. my thought is work done=totat kinetic energy so, 150 joules= 1/2(1)v^2 + 1/2(3)v^2

2. Jan 7, 2008