Forces
A force is something which causes an object to:
accelerate
change velocity
change direction
speed up
slow down
A force is measured in newtons (N)
- Newton meter
| <<Force<< | }}Effect}} | [[Example[[ |
|---|---|---|
| Push | Change direction or speed | Pushing a child |
| Pull | Change direction of speed | Pulling a door |
| Weight | Pulls things towards the centre of the earth | Pen dropping |
| Friction | Slows things moving over each other | Brakes |
| Stretching | Change shape of an object | A hair tie |
| Compression | Changes shape of an object | Sitting on a pillow |
Balance
- If the forces on an object are balanced the object remains at a constant velocity
- If the forces on an object are balanced the object accelerates
Friction
Friction is a force which opposes movement between two things touching
- The rougher that two surfaces are, the more friction there is
We can reduce friction with:
- Lubricant
- Oil in car engine
- Streamlining in design to reduce friction
- F1 cars
- Ball bearings
- Fidget spinners
Advantages of friction
- Gives fingers grip
- Tyres and shoes grip to move
- Brakes
- Slows down rain and hail
Disadvantages of friction
- Unwanted noise and heat
- Wastes energy
- Wears things away
- Slows things down that we don’t want
Formula
Force = mass (kg) x acceleration (m/s²)
F = (m)(a)
Measured in Newtons (N)
Weight
The effect of gravity on object
Varies on different planets
Formula
Weight = mass (kg) x gravitational pull (N/kg)
Measured in Newtons (N)