Question

A 10,000 N piano is dropped from the top of a building. When the piano reaches terminal speed…

Answer 1

a). When the piano reaches terminal speed, it is no longer accelerating,
so the net force on it must be zero.

b). If the net force on the piano is zero, the upward force of air resistance on it
must be exactly equal to the downward force of gravity ... 10,000 N.