1) A 15 g bullet is shot into a 5085 g wooden block standing on a frictionless surface. The block, with the bullet in it, acquires a velocity of 1 m/s. Calculate the velocity of the bullet before striking the block.?2)What is the force on the head of a nail that is struck by a 1.5 kg hammer moving at 7 m/s. (The hammer is brought to rest in 0.001 s.)?
A) 10.5 N
B) 105 N
C) 1050 N
D) 10500 N
E) 105000 N
F) I haven't a clue.
3) A blue-green photon (484nm) is absorbed by a free hydrogen atom, initially at rest.
What is the recoil speed of the hydrogen atom after absoribing the photon?
4) A heat engine with a thermal efficiency of 25 % does 100j of work per cycle.
How much heat is extracted from the hot reservoir per cycle?
How much heat is exhausted to the cold reservoir per cycle?