Three blocks are in contact in a straight line on a frictionless horizontal surface

PHYSICS · Single correct · A Level · Physics · Mechanics and materials · Mechanics and materials

Problem

Three blocks are in contact in a straight line on a frictionless horizontal surface. From left to right, the masses are

m_1=1\,\text{kg}

m_2=2\,\text{kg}

, and

m_3=3\,\text{kg}

. A constant horizontal force of

18\,\text N

is applied to the left face of block

m_1

, pushing the entire stack to the right. What is the magnitude of the contact force exerted by block

m_2

on block

m_3

? (a)

6\,\text N

(b)

18\,\text N

(c)

9\,\text N

(d)

10.8\,\text N