Question

A 1.80-g hailstone, which can be modeled as a particle, falls a vertical distance of 155 m at constant speed. What is the work done on the hailstone by gravity and air resistance?
(a) gravity

J

(b) air resistance

J

Answer 1

It is at terminal velocity, constant speed, so the net force on it is zero.
There is a force down, -m g if plus is up
There is a friction force up, + mg if negative is down
It moves down, -150 meters
so
Work done by g = - m g (-150 ) = +150 m g Joules
Work done by friction = +mg (-150) = -150 m g Joules
m = 0 .0018 kg and g = 9.8 m/s^2