A penny is dropped from the top of a 180m building. How much time will it take to fall to the ground?

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.

Acar traveling at 22 m/s starts to decelerate steadily. it comes to a complete stop in 15 seconds. what is it’s acceleration?

Henry, whose mass is 95 kg, stands on a bathroom scale in an elevator. the scale reads 830 n for the first 2.4 s after the elevator starts moving, then 930 n for the next 2.4 s. part a what is the elevator's speed 4.8 s after starting? express your answer with the appropriate units.