Work done by a force is zero when the angle between the force and the displacement is
- A. 0 degrees
- B. 45 degrees
- C. 90 degrees
- D. 180 degrees
Explanation
Work is the scalar product Fd cos theta, and cos 90 degrees is zero, so a force perpendicular to the displacement does no work. This is why the centripetal force in uniform circular motion does no work and the speed stays constant. At 180 degrees the work is negative rather than zero, as with friction.
Related questions
A force of 50 N pulls a box 4 m along the floor at 60 degrees to the horizontal. The work done is
The work done by the centripetal force on a body moving in a circle at constant speed is
A force acts on a body but does negative work. This means the force
A porter carries a suitcase horizontally across a platform at constant speed. The work done by the porter against gravity is
Work is done on a body only when