physics
posted by HELP!!! on .
A 0.330kg block of wood rests on a horizontal frictionless surface and is attached to a spring (also horizontal) with a 29.5N/m force constant that is at its equilibrium length. A 0.0600kg wad of PlayDoh is thrown horizontally at the block with a speed of 3.00 m/s and sticks to it. Determine the amount by which the PlayDohâ€“block system compresses the spring?
i used conservation of energy and got 13.53 cm and its wrong.

Before applying conservation of energy law, you have to evaluate the speed of the block+wad system by applying conservation of impulse law:
m(block+wad)*V = m(wad)*V(wad)
So, find V and then use it in conservation of energy law (keep in mind that the the kinetic energy of block+wad system should be calculated using total mass (block+wad) and above evaluated speed V.