A 10 g copper nail driven into a board increases in temperature. Assume that 60% of the kinetic energy delivered by 1. 8 kg hammer with a speed of 7. 8 m/s is transformed into heat that flows into the nail and does not flow out. The nail is at room temperature t=293k, specific heat of copper is 390 j/(kg*k), melting temperature of copper is 1356k, and the heat of fusion for copper is 134x103 j/kg how many times do you have to strike the nail until it melts?.