Defining and calculating gravitational potential energy (mgh) and kinetic energy (½mv²), and applying the conservation of energy to falling objects, swings and pendulums.
5 narrated scenes. Press play, listen and read along — the points appear as they are explained. Use ‹ Prev / Next › or the scene bar to jump to any scene.
Drop a ball from a roof and its energy simply changes label: stored height energy becomes movement energy, with the total unchanged all the way down.
Narration uses your device’s built-in voice. No sound? Switch to “Captions only” — the captions advance on their own.
Watch potential and kinetic energy swap while the total stays constant.
Copy these into your notebook in your own words — that is how they stick.
Energy due to position or condition (raised, stretched, chemical).
E_p = mgh; unit J.
E_k = ½mv²; unit J.
E_k becomes four times as large.
Energy cannot be created or destroyed; it changes form.
mgh lost = ½mv² gained (no air resistance); v = √(2gh).
Max E_p at the ends; max E_k at the bottom.
Some energy becomes thermal (friction, air resistance).
3 quick games on this lesson. Earn XP and badges as you play — your best score for each game is saved. Games are for practice and do not change your exam readiness. More games in the Physics Arcade.
8 items modelled on real CSEC Paper 1 questions. Choose one answer for each, then check. Aim for 80% or better. Work each item on paper first.
Write full answers, then reveal the mark scheme and tick the points you earned (15 marks in total). Show all your working — method marks count. Your answers are saved on this device.
Question 1 [15 marks]
A ball of mass 0.50 kg is released from rest at a height of 5.0 m above the ground. Take g = 10 m/s² and ignore air resistance.
(a) (a) Define gravitational potential energy. [2]
(b) (b) Calculate the potential energy of the ball at the start. [3]
(c) (c) State the kinetic energy of the ball just before it hits the ground, and give a reason. [2]
(d) (d) Calculate the speed of the ball just before it hits the ground. [3]
(e) (e) Calculate the kinetic energy and the potential energy when the ball is 2.0 m above the ground. [3]
(f) (f) In practice the ball’s speed is slightly less than your answer to (d). Explain why. [2]
Find these in your own past-paper booklets for extra timed practice. Items above are written in the style of these papers; any adapted from a specific question say so.