Two blocks and of masses and respectively lie in contact on a smooth horizontal surface

PHYSICS · Subjective · AP · Physics 1: Algebra-based · Force and Translational Dynamics · Force and Translational Dynamics

Problem

Two blocks

P

and

Q

of masses

2\,\text{kg}

and

4\,\text{kg}

respectively lie in contact on a smooth horizontal surface. A constant horizontal force of

18\,\text{N}

acts on

P

from the left. (i) Find the magnitude of the acceleration of the two-block system. (ii) Calculate the magnitude of the horizontal force that block

Q

exerts on block

P

. (iii) Prove, by considering each block separately, that the forces at the common interface satisfy Newton’s third law.