Question

A particle P moves around the circle of radius R under the influence of a radial force of magnitude F as shown. What is the work done by the radial force as the particle moves from position 1 to position 2 halfway around the circle? 

(A) Zero 

(B) RF 

(C) 2RF 

(D) πRF 

(E) 2πRF

Answer 1

Correct option (A) Zero

Since the force is always perpendicular to the incremental distances traveled as the particle travels the loop, there is zero work done over each increment and zero total work as well.