The head of a 1.0 kg hammer; moving at 3.6 m/s. strikes a nail and drives it into hardwood.
a) The head stays in contact 2.0 m/s and rebounds with negligible velocity. What is the average force exerted on the nail.
b) When the same hammer hits a springy nail, it rebounds with its initial speed, 3.6 m/s. the contact time is the same. What force is exerted this time?