Question

A box slides to the right across a horizontal floor. A person called Ted exerts a force T to the right on the box. A person called Mario exerts a force M to the left, which is half as large as the force T. Given that there is friction f and the box accelerates to the right, rank the sizes of these three forces exerted on the box. 

(A) f < M < T 

(B) M < f < T 

(C) M < T < f 

(D) f = M < T 

(E) It cannot be determined.

Answer 1

Correct option (A) f < M < T

Given that the box accelerates toward Ted, Ted’s force must be greater than Mario’s force plus the force of friction. Since Mario’s force is ½ of Ted’s force, the force of friction must be less than half of Ted’s force.