Compute each part of given problem:
Problem: In compressing the spring in a toy dart gun, 0.2 J of work is done. When the gun is fired, the spring gives its potential energy to a dart with a mass of 0.04 kg.
Part A: What is the darts kinetic energy as it leaves the gun?
Part B: What is the darts speed?
Do not copy and paste from Google, explain your answer clearly.