iGCSE Work and Power

What is the work done in moving the pendulum with mass 0.25 kg through a height of 0.5 m?

• 0.125 J

• 0. 0.00125 J

• 1.25 J

• 2 J

Another pendulum has a mass of 200 g and falls through a height of 0.25 m. Assuming there is no air resistance, what is the pendulum’s maximum speed at the bottom of its fall (g = 10 m/s^2)?

• 2.2 m/s

• 5 m/s

• 10 m/s

• 100 m/s

Which of the following equations for calculating work done is correct?

• work done = power × time

• work done = energy transferred

• work done = force × distance in the direction of the force

• all of the above

A student lifts a 15 N mass through a distance of 1.5 m. What is the work done?

• 22.5 J

• 10 J

• 0.1 J

• 15 J

Which are the units of work?

• watts

• joules

• seconds

• N/m

A weightlifter lifts a barbell of mass 45 kg through a height of 0.75 m. What is the gravitational potential energy gained by the barbell (gravity = 10 N/kg)?

• 60 J

• 100 J

• 337.50 J

• 33.75 J

A motorcyclist is travelling at a speed of 35 m/s. The engine of the bike provides a force of 250 N to the motorbike. What is the work done by the motorbike in 1 second?

• 7 J

• 8750 J

• 140 J

• 10 000 J

A ball of mass 50 g is suspended at a height of 2.5 m from the ground. What would be the maximum value for kinetic energy the instant before the ball hits the ground? Assume air resistance is negligible.

• 0 J

• 1.25 J

• 12 500 J

• 1250 J

An asteroid of mass 500 kg approaches the Earth’s ground at a speed of 1000 m/s. What is the kinetic energy of the asteroid?

• 250 × 10^6 J

• 5.0 × 10^6 J

• 250 kJ

• 500 kJ

A pendulum of mass 0.25 kg is released from a height of 0.5 m. Assuming that the impact of air resistance is negligible, which of the following statements about energy transfer is correct?

• As the pendulum falls, the GPE decreases as KE increases.

• When the pendulum reaches the bottom of its swing, all GPE will have been transferred to KE.

• When the pendulum reaches the bottom of its swing, the pendulum will be travelling at its fastest speed.

• All of the above.