What the centre of gravity is, how to find it for a lamina with a plumb line, and how the position of the centre of gravity and the width of the base decide whether an object is stable.
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 double-decker bus can tilt a long way without toppling, yet a tall narrow shelf unit falls easily. The secret is where the weight line falls.
Narration uses your device’s built-in voice. No sound? Switch to “Captions only” — the captions advance on their own.
Tilt the block and find the angle at which it topples.
Copy these into your notebook in your own words — that is how they stick.
The point through which the whole weight of the body appears to act.
CG at the geometric centre.
Hang from 3 holes with a plumb line; the lines cross at the CG.
Returns when tilted slightly: CG rises.
Falls further: CG lowers.
Stays where placed: CG height unchanged.
The vertical line from the CG falls outside the base.
Lower the CG and widen the base.
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 (11 marks in total). Show all your working — method marks count. Your answers are saved on this device.
Question 1 [11 marks]
A student is asked to find the centre of gravity of an irregular piece of card.
(a) (a) Define the centre of gravity of a body. [1]
(b) (b) Describe how the student can find it using a plumb line, a pin and a stand. [4]
(c) (c) State how the student could check the result. [1]
(d) (d) A tall narrow bottle tips over at a smaller angle than a short wide one. Explain why. [3]
(e) (e) Name the type of equilibrium of a ball on a flat table and give a reason. [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.