Forces & Their Effects
Year 7 🚀 Forces & Motion Identify types of forces and understand balanced and unbalanced forces.
🚀 What is a Force?
A force is a push or pull that can change an object's shape, speed or direction. Forces are measured in Newtons (N).
| Type | Contact? | Examples |
|---|---|---|
| Gravity (Weight) | No | Pulling everything down |
| Normal Reaction | Yes | Floor pushing up on you |
| Friction | Yes | Slowing a sliding object |
| Tension | Yes | Force in a stretched rope |
| Magnetic | No | Magnets attracting iron |
⚖️ Balanced & Unbalanced Forces
When forces are balanced, an object stays stationary or moves at constant velocity. When forces are unbalanced, the object accelerates.
Resultant Force
$$F_{\text{resultant}} = \text{sum of all forces (with direction)}$$Example: A book on a table has weight 10 N down and normal force 10 N up → resultant = 0 N → balanced → stationary.
📏 Force Diagrams
We use force arrows (free body diagrams) to show all forces on an object. Arrow length = force size; arrow direction = force direction.
Always draw arrows from the centre of the object. The longer the arrow, the bigger the force.
Ready to test yourself? Click the Quiz tab above to answer questions on this topic!
🚀 Force Diagram Builder
Build a force diagram by setting force values below.