Topic 1 · pp. 53–56 · Free
Topic Notes · Easy summaries with diagrams
Chapter 3 — Chapter 3 — Dynamics
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Topic 1 of 5
📘Easy summary
A force is a push or pull that starts, stops, or changes the speed or direction of a body (it can also change shape). Unit: newton (N). Contact forces act at the point of contact — friction, tension, normal reaction, air resistance, applied push. Non-contact forces act at a distance — gravitational, magnetic, electrostatic. Four fundamental forces: gravitational, electromagnetic, strong nuclear, weak nuclear. Newton's law of gravitation: F ∝ m₁m₂/r².
⭐Key points
- Force meter (spring balance) measures force in N.
- Force is a vector.
🔬Diagram
🌿Real-life example
A magnet attracting a pin without touching it — non-contact force.
💡Exam tip
- Learn 5 examples of each type.
✅Quick check
1. Non-contact force:
2. Unit of force:
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