ok i just need an explanation for one tiny thing.
a drop-forge hammer of mass 1500kg falls under gravity on to a piece of hot metal which rests in a fixed die. from the instant the hammer strikes the piece of metal until it comes to rest, the hammer is decelerating at 1.5 ms^2.
find the magnitude of the force exerted by the hammer on the piece of metal while (a.) the hammer is decelerating (b.) after the hammer has come to rest.
of course b. was easy, 15000N
for a. i'm not sure, i know it has something to do with newton's third law. the answer is 17500 N but why would the force be greater while the hammer is decelerating? isn't deceleration just the difference between opposing forces divided by weight? in this case i would have answered that the force was 15000N as well.