Question

positive work is done when force is applied to an object in which of the following directions?
a upwards
b in the opposite direction that the object moves.
c in the same direction that the object moves.
d in a direction perpendicular to the direction that the object moves.

Explanation:

The formula for work is \( W = Fd\cos\theta \), where \( F \) is force, \( d \) is displacement, and \( \theta \) is the angle between them. For work to be positive, \( \cos\theta> 0 \), which occurs when \( \theta = 0^\circ \) (force and displacement in the same direction). Option a (upwards) depends on motion direction. Option b (\( \theta = 180^\circ \), \( \cos\theta=- 1 \), negative work). Option d (\( \theta = 90^\circ \), \( \cos\theta = 0 \), zero work). So positive work is when force is in the same direction as object’s motion.

Answer:

c. In the same direction that the object moves.