JC Science Physics raiped revison

Length

is the straight-line distance between two points in space.

Mass

is the quantity of matter in a body

Time

is the quantity in which change happens.

Temperature

is a measure of how hot or cold a body is.

Area

is the amount of surface that covers a body.

Volume

is the amount of space taken up by a body.

Area

length x width

Volume

length x width x height.

The density of a body is

the mass of one unit of volume of a body.

Density

(mass / volume)

Speed

is the distance travelled by an object in a unit of time

Velocity

is the speed of a body and the direction in which it is moving.

Acceleration

is the change in velocity in a unit of time.

Speed

distance / time.

Acceleration

change in velocity / time taken for the change.

A force

gives a body at rest a velocity or makes a moving body change its velocity.

A force

causes a mass to accelerate.

A change in velocity

can be a change in speed or a change in direction or both.

Friction

is a force that opposes the motion of a body when it is in contact with another

Lubrication

is when a material is placed between surfaces of two moving bodies in contact, to reduce friction.

The centre of gravity of a body

is a point about which the turning effects caused by gravity are balanced. The weight of the body seems to be concentrated at this point.

A body is in equilibrium if

its centre of gravity is not moving and the body is not turning about any point

A lever is

a rigid body that can rotate about a fulcrum.

The turning effect of a force

is called the moment of a force.

The law of the lever states

that when a lever is balanced, the sum of the clockwise moments equals the sum of the anticlockwise moments.

Pressure

is the amount of force acting on a unit area.

Work done

Force x distance moved in the direction of the force

Energy

is the ability to do work

Power

is the amount of work done in a unit of time.

Energy

is neither created nor destroyed but can be converted from one form to another.

Heat

is a form of energy

Temperature

is a measure of the relative hotness or coldness of a body.

Increase in pressure

raised the boiling point of water.

Latent heat is

The heat that is needed to change the state of a substance.

Conduction

is the transfer of heat through a substance without any overall movement of the substance itself.

Convection

is the transfer of heat through liquids and gases by the mass movement of particles.

Radiation

is the transfer of heat by means of waves that can travel through a vacuum. This is how the heat energy of the sun gets to the Earth.

Light

is a form of energy because it is a wave and waves carry energy.

A luminous body

creates its own light.

Non - luminous bodies

reflect light.

Dispersion

The breaking up of white light into its different colours

The spectrum of light is made up of seven major colours.

Red orange yellow green blue indigo and violet.

Refraction

is the bending of light as it passes from one transparent material to another.

Sound

is a form of energy and is produced when bodies vibrate.

Sound

needs a medium to be transmitted.

The speed of sound

is much less than the speed of light.

A force

something that changes the motion of a body.

A magnetic field

is the region of space around a magnet in which certain materials and other magnets will experience a magnetic force.

A compass

is a small magnet or a magnetised needle that is free to move in a protective case.

Voltage

Resistance x Current or V \= RI

Direct current

is the flow of charge in only one direction around a circuit.

Alternating current

is current that constantly changes direction.

A kilowatt - hour

is the amount of energy provided when 1 kilowatt of power is used for one hour.

Cost

power rating in kW x unit cost x time in hours.

Electronics

is the controlling of devices by directing small amounts of current around circuits.