The turning effect of a force, calculating moments (force × perpendicular distance), applying the principle of moments to balanced beams and see-saws, and the action of levers.
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.
A long spanner loosens a stubborn nut that a short one cannot. The longer the distance from the pivot, the greater the turning effect.
Narration uses your device’s built-in voice. No sound? Switch to “Captions only” — the captions advance on their own.
Move the masses along the beam until the moments balance.
Copy these into your notebook in your own words — that is how they stick.
M = F × d, with d the PERPENDICULAR distance from the pivot; unit N m.
Increase with a bigger force or a longer perpendicular distance.
No resultant force and no resultant moment.
Clockwise moments = anticlockwise moments about any point.
Upward forces = downward forces.
Its weight acts at its centre.
Fulcrum, effort, load; a long effort arm needs a small effort.
N m is not J: moment is a turning effect; energy is force × distance moved.
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 uniform metre rule of weight 1.0 N is pivoted at its centre (50 cm mark).
(a) (a) State the principle of moments. [2]
(b) (b) A 4.0 N weight is hung at the 20 cm mark. Calculate its moment about the pivot. [3]
(c) (c) A second weight W is hung at the 80 cm mark to balance the rule. Calculate W. [3]
(d) (d) Calculate the upward force of the pivot on the rule. [2]
(e) (e) State the effect on the balance if the 4.0 N weight is moved to the 10 cm mark. [2]
(f) (f) Identify the effort, load and fulcrum when a wheelbarrow is used to carry soil. [3]
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.