Conservation of energyAQA A-Level Physics: Flashcards
What these 12 flashcards ask
- State the principle of conservation of energy.
- Write the equation for the change in gravitational potential energy near the Earth's surface.
- Write the equation for kinetic energy.
- What happens to the kinetic energy if the speed doubles?
- What is the speed of an object that has fallen a height h from rest, with no air resistance?
- Where does the energy go when a skier slows because of friction?
- How do you find a mean resistive force from energy?
- Why is the rebound height of a bouncing ball less than the drop height?
- Why does mass not affect the speed of a falling object when air resistance is ignored?
- What is the unit of energy?
- A 2.0 kg object is lifted 3.0 m. What is the gain in gravitational potential energy? (g = 9.81 N kg⁻¹)
- An object is thrown upwards at 12 m s⁻¹ and air resistance is ignored. How high does it rise?
Exam questions on Conservation of energy
- A ball of mass 0.15 kg is released from rest at a height of 3.2 m above a hard floor. Ignore air resistance until the ball hits the floor. Take g = 9.81 N kg⁻¹.The ball rebounds from the floor to a height of 2.4 m. Calculate the energy dissipated in the impact with the floor.2 marks
- A pendulum bob of mass 0.50 kg is held at rest with the bob 0.20 m above the lowest point of its swing, then released. Assume that air resistance and friction at the pivot are negligible. Take g = 9.81 N kg⁻¹.A second bob of mass 1.0 kg is released from the same height. Explain, using energy, why its speed at the lowest point is the same as that of the first bob.2 marks
- A skier of mass 70 kg starts from rest at the top of a straight ski slope that is 600 m long and has a vertical drop of 150 m. At the bottom of the slope the skier is moving at 20 m s⁻¹. Take g = 9.81 N kg⁻¹.Explain what happens to the gravitational potential energy lost by the skier.3 marks
Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).