A rock of mass 32 kg accidentally breaks loose from the edge of a cliff and falls straight down. The magnitude of the air resistance that opposes its downward motion is 275 N. What is the magnitude of the acceleration of the rock?

Answer 1

(Weight - 275 N)/Mass = acceleration

Weight = 313.6 N

a = (313.6-275)/32 = 1.2 m/s^2

This accleration can only apply for an instant

Actually, acceleration will decrease and velocity and air resistance will increase until a limiting velocity is reached and acceleration becomes zero. This is a misleading problem.