Level: JHS, Basic 7 | Subject: Integrated Science | Strand: Forces and Energy | Topic: Force and Motion
Curriculum reference: B7.4.4.1 (NaCCA Integrated Science).
1. What is a Force?
- A force is a push or a pull on an object.
- The unit of force is the newton (N). It is measured with a spring balance (newton meter).
- A force can make an object start moving, stop, speed up, slow down, change direction or change shape.
2. Types of Force
| Force | What it does | Example |
|---|---|---|
| Gravity (weight) | Pulls objects towards the Earth | A mango falling from a tree |
| Friction | Opposes motion between surfaces | A football slowing down on grass |
| Magnetic force | Attracts or repels magnetic materials | A magnet picking up pins |
| Muscular force | Push or pull by our muscles | Pushing a wheelbarrow |
| Elastic (spring) force | Returns a stretched object to its shape | A catapult or a spring |
- Friction is useful for walking and braking, but it wears out tyres and shoes and makes heat. Oil and grease reduce friction.
3. Inertia and Newton’s First Law
- Inertia is the tendency of an object to stay at rest or to keep moving in a straight line at the same speed.
- Newton’s first law: an object stays at rest, or keeps moving at constant speed in a straight line, unless an unbalanced force acts on it.
- Heavier objects have more inertia. A loaded truck is harder to start and harder to stop than a bicycle.
- Examples: passengers lean forward when a tro-tro brakes suddenly; they fall backwards when it starts quickly. This is why we wear seat belts.
4. Magnets
- A magnet attracts magnetic materials: iron, steel, nickel and cobalt.
- Non-magnetic materials include wood, plastic, glass and copper.
- Every magnet has two poles: north and south, where the pull is strongest.
- Like poles repel. Unlike poles attract.
- A freely hanging magnet points north and south, which is how a compass works.
- Uses: compasses, fridge doors, electric bells, speakers, door catches, separating iron from rubbish.
- Keep magnets away from phones, cards and televisions. Do not drop or heat them, as this weakens them.
Remember: Force is a push or pull measured in newtons. Inertia is the tendency to resist change in motion. Like poles repel and unlike poles attract.
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Education Always (education.inspiringalways.com). Original notes written to follow the NaCCA Basic 7 Integrated Science curriculum.