A stone weighing 2 pounds is attached to the end of a four-foot string and is whirled horizontally with one end held fixed. It makes 1 revolution per second. Find the work done by the Force F that keeps the stone moving in a circular path. [Hint: Use Force = (mass)(centripetal Acceleration).] Round your answer to two decimal places, if required.
A) $201.06 \mathrm { ft } \cdot \mathrm { lbs }$
B) $0.00 \mathrm { ft } \cdot \mathrm { lbs }$
C) $804.25 \mathrm { ft } \cdot \mathrm { lbs }$
D) $256.00 \mathrm { ft } \cdot \mathrm { lbs }$
E) $12.57 \mathrm { ft } \cdot \mathrm { lbs }$

Question

A stone weighing 2 pounds is attached to the end of a four-foot string and is whirled horizontally with one end held fixed. It makes 1 revolution per second. Find the work done by the Force F that keeps the stone moving in a circular path. [Hint: Use Force = (mass)(centripetal Acceleration).] Round your answer to two decimal places, if required. 
A) $201.06 \mathrm { ft } \cdot \mathrm { lbs }$
B) $0.00 \mathrm { ft } \cdot \mathrm { lbs }$
C) $804.25 \mathrm { ft } \cdot \mathrm { lbs }$
D) $256.00 \mathrm { ft } \cdot \mathrm { lbs }$
E) $12.57 \mathrm { ft } \cdot \mathrm { lbs }$

Quizplus · Accepted Answer

Work done in maintaining an object in circular motion at constant speed is zero because the force is perpendicular to the direction of motion, and work is calculated as the dot product of force and displacement. In circular motion at constant speed, there is no displacement in the direction of the force.

A Stone Weighing 2 Pounds Is Attached to the End 201.06ft⋅lbs201.06 \mathrm { ft } \cdot \mathrm { lbs }201.06ft⋅lbs

A Stone Weighing 2 Pounds Is Attached to the End $201.06 \mathrm { ft } \cdot \mathrm { lbs }$