Forces resources

Physics, grade 8. Notes, worksheets, videos, interactive tools and revision materials for this chapter.

Notes

Study notes

The chapter's lessons are the notes — read them in order, then use the resources below.

01Newton's Laws of MotionThe three laws that govern how everything moves.Read lesson →02Types of ForcesMeeting contact forces like friction and non-contact forces like gravity and magnetism.Read lesson →03Balanced and UnbalancedUsing force diagrams to see when forces cancel out or cause acceleration.Read lesson →04Friction and DragExploring how surfaces and air resistance oppose motion — and when that helps.Read lesson →

Worksheets

Practice worksheet

Attempt every question before revealing the answer — that struggle is where learning happens.

1. State Newton's three laws of motion in your own words.

Think: keep doing what you're doing / F = ma / every action…

1) Objects keep their state of motion unless a resultant force acts. 2) F = ma — acceleration is proportional to resultant force. 3) Every action has an equal and opposite reaction.

2. A 2 kg trolley accelerates at 3 m/s². What is the resultant force?

F = ma. Watch the units.

F = 2 × 3 = 6 N.

3. Explain, using Newton's third law, how a rocket moves forward in space.

What does the rocket push on?

The rocket pushes exhaust gases backwards (action); the gases push the rocket forwards with an equal and opposite force (reaction). No air is needed.

4. A car of mass 1200 kg needs to accelerate at 2.5 m/s². The engine provides 4000 N. Is that enough? (Ignore other forces.)

Calculate the force actually required.

Required F = 1200 × 2.5 = 3000 N. 4000 N > 3000 N, so yes — with 1000 N to spare.

Videos

Watch and learn

Hand-picked searches to find a clear video explanation of each lesson.

Newton's Laws of Motion — explainedYouTube search · opens in a new tabWatch →Types of Forces — explainedYouTube search · opens in a new tabWatch →Balanced and Unbalanced — explainedYouTube search · opens in a new tabWatch →Friction and Drag — explainedYouTube search · opens in a new tabWatch →

Revision

Revision checklist

Can you explain each of these out loud, without looking? If not, re-read that lesson.

Newton's 1st law: objects maintain their velocity unless a resultant force acts.
Newton's 2nd law: F = ma — resultant force equals mass × acceleration.
Newton's 3rd law: every action has an equal and opposite reaction.
Weight is a force (mass × gravitational field strength), measured in newtons.
Free-body diagrams show all forces acting on one object — draw them before calculating.

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