Force and motion is the part of SPM Science where numbers and explanations meet. It covers how fast and how quickly speed changes, what a graph of motion tells you, how a force changes motion, and why objects resist that change.
The lessons below follow one order, so each idea is ready when the next lesson needs it. You can start anywhere if a particular skill is weak, but the order is the quickest route for a student meeting the topic fresh.
How do the parts connect?
Speed and acceleration come first because they describe motion without asking why it happens. Reading motion graphs then lets you see the same quantities as shapes.
Force and momentum explain why the motion changes. Inertia is the conceptual side of the same idea, and it is tested by explanation rather than by calculation. The electricity and energy in quantitative contexts cluster reuses the habit of formulas with units.
A small example that touches every part
An invented trolley rolls 12 m along a bench in 4 s. Its average speed is 12 ÷ 4 = 3 m/s.
On a distance-time graph, that journey would be a straight line rising to 12 m at 4 s, and the slope of the line is the speed. If the trolley then hits a soft stopper and halts, the graph goes flat, because the speed is now zero.
A passenger-style question follows: a cup of water on the trolley spills forward when the trolley stops. The cup keeps moving because of inertia, since no force stopped it at the same moment as the trolley.
One scene has used speed, a graph, a force and inertia. Exam questions on this topic often combine ideas in the same way, in one short scenario.
Who should start where?
- New to the topic: begin with calculating speed, velocity and acceleration.
- Comfortable with calculations but weak on graphs: go to reading motion graphs.
- Formulas fine, explanations thin: try explaining inertia using safe thought experiments.
- Ready to test yourself: use the force and motion practice set.
After the topic, apply it to a teacher’s questions through online one-to-one Science tuition. The motion-graph explorer lets you draw a graph and watch the speed change.