BECE Force, Work, and Energy 3

Question 1

A boy carries a heavy load horizontally across a room at constant height. How much work does gravity do on the load?

Accepted Answer

Zero work

Answer

Gravity acts vertically downward while displacement is horizontal, so the angle between them is 90°, giving zero work (W = Fd cosθ = Fd cos90° = 0).

Question 2

Which energy transformation occurs when a stretched rubber band is released and flies across the room?

Accepted Answer

Elastic potential → kinetic

Answer

The elastic potential energy stored in the stretched rubber band converts to kinetic energy as it moves.

Question 3

Friction between two surfaces always acts in which direction relative to motion?

Accepted Answer

Opposite to the direction of motion

Answer

Friction is a resistive force that always opposes the direction of motion or intended motion.

Question 4

A pendulum swings from its highest point to the lowest point. What happens to its energy?

Accepted Answer

Potential energy decreases; kinetic energy increases

Answer

As the pendulum falls to its lowest point, gravitational potential energy converts to kinetic energy (ignoring air resistance).

Question 5

A force of 50 N acts on an object but the object does not move. How much work is done?

Accepted Answer

0 J

Answer

Work requires displacement; if the object does not move (d = 0), then W = F × 0 = 0 J.

(BECE) Basic Education Certificate Examination Practice Test