Question

Lucy (60 kg) pushes against Sarah (90 kg) with a force of 540 N directed east .
(a) what force does sarah exert on Lucy ?
(b) what acceleration does each person experiences?​

Answer 1

Answer:

Suppose the pusher is fixed, and the object moves with constant acceleration.

Force required for the acceleration is m x a = 90 x 4/3 = 120 N [NOT 90x2]**

Force resisting motion = 200 - 120 = 80 N

Object’s normal force is 90 x 9.81, so Friction coefficient is 80 / (90 *9.81)

**[Mazmanian noted an error in A2’s acceleration value - 6 meters in 3 seconds from standstill implies an average velocity of 2 m/s Hence the end velocity is 2 x 2 m/s = 4 m/s, achieved in 3 seconds at 4/3 m/s^2]