Forces Flashcards
Formula for Weight
Weight = mass x gravitational force
Formula for pressure
Force/ Area
Formula for density
Mass/ volume
Mass
- Measurement of the amount of matter in an object (Kg)
- Mass does not change even when placed at different locations.
- It is NOT a force
Weight
- Measurement of the gravitational force acting on an object (N)
- Weight may change with location, depending on the strength of the pull of gravity
- is a force
Force
A force is either a push or a pull
Contact force
Contact forces are forces that exist between objects that are in contact with each other
E.g. Frictional force, Elastic force
Non- contact forces
Non-contact forces are forces that do not require forces to be in contact with each other
E.g. Magnetic force, Gravitational force
Gravitational force
The pull exerted by the Earth’s gravity on any object towards the centre of the Earth.
elastic force
The force acting on a stretched or compressed object to return it to its original shape.
magnetic force
The push or pull exerted between magnets or the pull of magnets on magnetic materials.
friction
Friction is a force that opposes motion between surfaces in contact.
Pressure
Pressure is the force acting normally per unit area.
Resultant force
When a number of forces can effectively be replaced with a single force called the resultant force or net force
Positive effects of friction
- Needed for holding things (prevents slipping)
- Used in braking pads to slow down cars
- Provides grip for objects
Negative effects of friction
- Causes heat to be produced (wastage of energy)
- Causes wear and tear of moving parts in engines, motors and machines
Factors affecting friction
- Type of surface
- Mass of objects
Relationship between the force exerted on an object/ the area on which the force is exerted, and pressure
- For the same area given, the greater the force exerted, the greater the pressure
- For the same force applied, the greater the area in which the force is exerted, the greater the pressure
Pressure for liquids
- The deeper the object is, the greater the pressure it experiences due to the liquid
- This is because the deeper an object is, the greater the amount of water presses down on it and hence, there will be more pressure
Atmospheric pressure
Atmospheric pressure is the pressure that the air above us exerts one us. It decreases at higher altitudes
Density
Density is defined per unit volume
Effects of density
- Density of solid is greater than density of liquid= solid sinks
- Density of solid is the same as the density of liquid= solid will be suspended
- density of solid is lower than density of water= solid floats
