A 2kg mass is loaded into a spring cannon. The cannons spring has a constant k=4000N/m and the spring is compressed 0.8m. The mass is initially at rest. The flat surface is entirely made of a substance with a coefficient of kinetic friction of 0.6. All the energy in the spring is converted to kinetic energy. there is no friction in the cannon.
1) Before the mass is released, what is the potential energy of the spring?
2) What is the kinetic energy of the mass the moment after release?
3) what is the initial velocity of the mass?