The effects of forces, the types of force, the difference between mass and weight (W = mg), and how derived quantities and their units, such as the newton, are built from base units.
4 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.
Your mass is the same on the Moon, but your weight is six times smaller. The difference is the key to many Paper 1 questions.
Narration uses your device’s built-in voice. No sound? Switch to “Captions only” — the captions advance on their own.
Copy these into your notebook in your own words — that is how they stick.
A push or pull; vector; newton (N). Can change shape, size or motion.
Gravitational, electric, magnetic, nuclear; contact forces (friction, tension, reaction, upthrust, air resistance).
Amount of matter; scalar; kg; constant everywhere.
W = mg; vector, downward; N; varies with g.
10 N/kg (= 10 m/s²) on Earth; about 1.6 N/kg on the Moon.
1 N = 1 kg m s⁻².
1 Pa = 1 N/m² = 1 kg m⁻¹ s⁻².
1 J = 1 N m = 1 kg m² s⁻²; 1 W = 1 J/s.
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 (14 marks in total). Show all your working — method marks count. Your answers are saved on this device.
Question 1 [14 marks]
Take g on Earth as 10 N/kg and g on the Moon as 1.6 N/kg.
(a) (a) Distinguish between mass and weight. [3]
(b) (b) Calculate the weight on Earth of a student of mass 55 kg. [3]
(c) (c) Calculate the weight of the same student on the Moon. [2]
(d) (d) State the mass of the student on the Moon. [1]
(e) (e) Show that the unit of force, the newton, can be written as kg m s⁻². [3]
(f) (f) State two effects that a force can have on a body. [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.