PHYSICS · Subjective · AP · Physics 1: Algebra-based · Force and Translational Dynamics · Force and Translational Dynamics
Problem
A boy of mass 60kg stands at rest on a light, frictionless skateboard of mass 5kg in front of a rigid wall. He suddenly places his palms against the wall and pushes it so that his hands are in contact for 0.50s. During this interval the average force exerted by the boy on the wall is 120N.
(a) Identify the action and reaction forces involved during the push.
(b) Calculate the magnitude of acceleration of the boy–skateboard system while his hands are in contact with the wall.
(c) Determine the speed with which the boy and skateboard move immediately after his hands lose contact with the wall.
(d) State the direction of this motion with respect to the wall and justify your answer briefly.