Which statement about work and angle is true?

• A. Work is always maximal regardless of direction
• B. Work is independent of angle between force and displacement
• C. Work is zero when force is perpendicular to displacement
• D. Work equals force times distance when the force is perpendicular

Answer: (C)

Work depends on how much of the force acts in the same direction as the movement. For a constant force, the work done is W = F · d = F d cos θ, where θ is the angle between the force and the displacement.

If the force is perpendicular to the displacement, θ = 90°, and cos 90° = 0, so W = 0. That means no work is done by a force that points sideways to the motion, even though the force might be strong.

The other statements fail because work changes with the angle: the work isn’t always maximal, nor is it independent of angle. And “force times distance” is only true when the force is in the same direction as the displacement (θ = 0); otherwise you multiply by cos θ, which reduces the work, and at 90° it becomes zero.