When dr. hewitt drops a book and a crumpled piece of paper together from the same height, which one hits the ground first?

When you push downward on a book at rest on a table, you feel an upward force. does this force depend on friction? defend your answer.

An electron is traveling with initial kinetic energy k in a uniform electric field. the electron comes to rest momentarily after traveling a distance d. (a) what is the magnitude of the electric field

Amass weighing 24 pounds, attached to the end of a spring, stretches it 4 inches. initially, the mass is released from rest from a point 8 inches below the equilibrium position. find the equation of motion. (use g = 32 ft/s2 for the acceleration due to gravity.)