Knowledge Organiser: Forces and Their Effects
This topic summary covers Knowledge Organiser: Forces and Their Effects within Forces & Their Effects for GCSE Physics. Revise Forces & Their Effects in Forces for GCSE Physics with 25 exam-style questions and 11 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 13 of 13 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 13 of 13
Practice
25 questions
Recall
11 flashcards
Knowledge Organiser: Forces and Their Effects
Key Terms
- Force: Push or pull — vector, measured in N
- Mass: Amount of matter — scalar, kg, constant
- Weight: Gravitational force — vector, N, varies
- Resultant force: Net single equivalent force
- Contact force: Requires physical touch
- Non-contact force: Acts at a distance
Key Facts
- Contact: friction, tension, normal force, air resistance, upthrust
- Non-contact: gravity, magnetic, electrostatic
- Zero resultant = constant velocity (or stationary)
- Non-zero resultant = acceleration
- g = 10 N/kg on Earth, 1.6 N/kg on Moon
Key Equations
- W = mg (Weight = mass × g)
- Forces same direction: add magnitudes
- Forces opposite direction: subtract magnitudes
Exam Tips
- Weight always in Newtons, never kg
- Free body diagram: one object, all forces on it
- Balanced ≠ no forces — just zero resultant
- State contact/non-contact type in every answer
Common Mistakes
- Giving weight in kg instead of Newtons: Weight is a force measured in Newtons — mass is in kg; W = m × g converts between them
- Saying balanced forces means no forces acting: Balanced forces means the resultant is zero — forces are still present and acting, they just cancel out
- Drawing forces from the wrong point: In free body diagrams, all forces must be drawn as arrows from the centre of the object (or its surface), not floating nearby
- Confusing mass and weight: Mass (kg) is the amount of matter; weight (N) is the gravitational force on that mass — weight changes on different planets, mass does not
- Forgetting to include all forces: Always check for weight (downward), normal/contact force, friction, and any applied forces — missing one force means the resultant is wrong
Revise this topic interactively on PrepWise — self-test mode, tap-to-reveal definitions, and Common Mistakes from examiners.
Try the interactive Knowledge Organiser — free →Keep building this topic
Read this section alongside the surrounding pages in Forces & Their Effects. That gives you the full topic sequence instead of a single isolated revision point.
Practice Questions for Forces & Their Effects
What is a force?
Explain what is meant by the resultant force on an object.
Quick Recall Flashcards
25 questions on Forces & Their Effects — practise free
Instant marking, adaptive difficulty, and 11 spaced repetition flashcards. Free until your GCSEs.
Try PrepWise Free