A stone (the system)with a mass of 1.0 kg is tied to the end of a light string which keeps it moving in a circle with a constant speed of 4.0 m/s on a perfectly smooth horizontal tabletop.The radius of the path is 0.60 m.How much work does the force exerted by the string do on the stone as it makes one-half of a complete circle?
A)100 J
B)3.8 J
C)0 J
D)40 J
E)80 J

Question

Quizplus · Accepted Answer

The work done by a force is given by the equation W = F*s*cos(theta), where s is the displacement of the object and theta is the angle between the force and displacement vectors. In this case, the force exerted by the string is always perpendicular to the displacement of the stone, so theta = 90 degrees and cos(theta) = 0. Therefore, the work done by the force is zero.

A Stone (The System)with a Mass of 1