1. Forces
1.1. Is a push or pull
1.2. Examples of push and pull
1.2.1. Lifting
1.2.2. Bending
1.2.3. Stretching
1.2.4. Twisting
1.2.5. Squeezing
1.3. Effects of forces
1.3.1. Change the speed of a moving object
1.3.2. Change the shape or size of an object
1.3.3. Make an object move or stop a moving object
1.3.4. Change the direction of a moving object
1.4. Measurements
1.4.1. Use Force-meters to measure force
1.4.1.1. Spring balance is a force meter
1.4.2. Types of spring balances
1.4.2.1. Extension Spring Balance
1.4.2.1.1. Stretches when a force pulls on it
1.4.2.1.2. The greater the force, the more the spring stretches
1.4.2.2. Compression Spring Balance
1.4.2.2.1. The spring is compressed when a force acts on it
1.4.3. SI Unit
1.4.3.1. Newton (N)
2. Important Forces Around Us
2.1. Frictional Force
2.1.1. Occurs when two moving surfaces are in contact
2.1.2. Causes a moving object to slow down and stop
2.1.3. Produces heat
2.1.4. Advantages
2.1.4.1. Prevents us from slipping and falling
2.1.4.2. Friction between our feet and ground gives a better grip needed for any movements
2.1.4.3. We can fix the nail in the wood or wall as it is friction which holds the nail
2.1.5. Disadvantages
2.1.5.1. Causes wear and tear
2.1.5.2. Hinders movement
2.1.6. Ways to reduce friction
2.1.6.1. Use a smooth surface
2.1.6.2. Use ball bearings or rollers
2.1.6.3. Use lubricants
2.1.6.4. Use streamlining
2.2. Magnetic Force
2.2.1. Magnet exerts a force called magnetic force
2.2.2. Examples of magnetic forces
2.2.2.1. Needle of compass
2.2.2.2. Door of a cabinet
2.2.2.3. Crane that that lifts iron and steel objects
2.2.3. A magnet made of iron and steel can attract objects
2.2.4. Forces Between Magnets
2.2.4.1. A magnet can exert a force on another magnet
2.2.4.2. Like poles repel
2.2.4.3. Unlike poles attract
2.3. Gravitational Force
2.3.1. Pulls objects towards the Earth
2.3.2. Exists between any two objects
2.3.3. Acts towards the center of a mass of an object
2.3.4. Weight
2.3.4.1. The gravitational force on Earth is equal to the force that the Earth exerts on you
2.3.4.2. Weight of an object depends on the force of gravity pulling on that object.
2.3.4.3. Can be measured using a spring balance and is measured in newtons (N)
3. Pressure
3.1. Depends on force and area
3.2. The amount of force that presses on a certain area is known as pressure
3.3. Increasing pressure by reducing area
3.3.1. When a smaller surface is in contact with an object, the pressure exerted is higher
3.4. Reducing pressure by increasing area
3.4.1. When a larger surface is in contact with the ground, the pressure exerted is lower
4. Calculating Pressure
4.1. Pressure is the force acting per unit area
4.2. SI Unit
4.2.1. Pascal (Pa)
4.3. Pressure= Force/Area
4.4. Area: Centimetre Square or Metre Square
4.4.1. Pressure : N/cm square Pa (Pascal) : N/m square