We have moved on to the topic of Friction today for Science. Here are the learning points:
- Friction is a force that opposes motion. It slows down motion / movement.
- Friction can be classified into its advantages or disadvantages. It is useful when it helps us to grip onto items such as pen or pencil to do writing. It is useful as it allows us to walk without slipping. It is not useful when friction gives out excess heat that results in energy loss. It is also not useful when friction causes wear and tear.
- In the example of a car moving on the road over a long period of time, it is useful as friction helps it to move without skidding. But friction causes heat and the tyres will wear out after a period of time. When not replaced, it will cause the car to skid and slide.
- Friction always acts in the opposite direction of the movement of an object.
- Concept: The rougher the surface, the greater the amount of friction.
- Ways to overcome friction:
- Oil the surface or object
- Lubricate the surface or object
- Add rollers or ball bearings to the base of the object (More ball bearings and rollers added will result in lesser friction to overcome)
- There are two kinds of friction (Static friction occurs when an object is stationary) (Kinetic friction occurs when an object is moving)
Reminders:
- Sign your exam papers for English and Science and show me tomorrow before filing
- Bring your energy workbook and English file tomorrow if you have not done so
- Dictation Unit 4 test is on tomorrow.
Thank you,
Sincerely,
Mr Nelson Ong
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