CXC Physics

The acient greeks

Did not carry out experiments they just guessed what something was

Aristole

observed and made assumptions based on his observations but did not carry out experiments

Galileo Galielei

The father of science who was the first the carry out experiments and invented the instruments to do so

Sources of error

Anything that can cause an incorrect value (or reaction) in an experiment

Precautions

Something that is done to eliminate of reduce a source of error

Linear scale

A scale on which the value of the quantity being measured is represented by an equal distance on the scale

Non Linear Scale

A scale on which the value of the quantity being measured is represented by unequal distances on the scale

Square area

Length x Length

rectangle area

length x width

triangle area

1/2base x height

cricle area

pi x r^2

parallelogram area

base x perpendicular height

trapezium area

1/2(side a + side b) x height

Volume definition area

The amount of space that a substance occupies

Volume of cuboid

height x width x length

volume of triangular prisim

1/2base x height x length

volume of cylinder

pi x r^2 x length

volume of trapezim prisim

1/2 (side a x side b) x height x length

Displacment method

This is the method used to find the volume of irregularly shaped objects

density formula

mass/volume

mass formula (volume)

desity x volume

volume formula

mass/density

Force definition

This can be described as a push or a pull and is measured in Newtons (N)

3 Types of force

Gravitational, Electric and Friction

What can force cause?

Change in shape, size, speed and direction

Mass definition

the amount of particles that make up an object

Weight formula

mass x gravitational field strength

mass formula (Force)

weight/gravitational field strength

gravitational field strength

weight/mass

gravitational field strength on earth is...

10N/Kg

gravitational field strength on the moon is...

1.6N/Kg

Hookes Law states that

the extension of a spring or any elastic body is directly proportional to the stretching force provided that the spring has not past its elastic limit

stretching force (F)

spring constant x extension

extension (e)

stretching force/spring constant

spring constant (k)

fretching force/extension

Relative density

This is the desity of a substance divided by the density of water.

Obedience to Hooke's law

A graph of force against extension must produce a straight line. If the spring exceeds the elastic liit the graph curves

Moment of force definition

this is the force multiplied by the perpendicular distance from the turning point

Moment of force (m or T)

Force x distance

Force (in moment of force [F])

moment of force/distance

Distance(In moment of force [x or s or d])

moment of force/force

The principle of moments states that

For a system that is in equlibrium the sum of the clockwise moments about one point must be equal to the sum of the anti clockwise moments about the same point

centre of gravity definition

This is the point of the object where the whole weight of it acts

factors that affect stability

centre of gravity (The lower the centre of grvity the more stable an object is)

area (The broader the base the more stable an object is)

Scalar quantities definition

this is a quantity that has size or magnitude only

Vector quantities definition

this is a quantity that has both magnitude and direction

acceleration formula (using v and u)

(a)

final speed - initial speed /

time

time formula (using v and u)

(t)

final speed - initial speed/

acceleration

final speed (v)

initial speed + (acceleration x time)

initial speed (u)

final speed- (acceleration x time)

speed ( in kinematics)

distance/

time

time (in kinematics)

distance/

speed

distance (in kinematics)

time x speed

formula for distance when all values are given

distance = ut + 1/2at^2

formula for velovity (or speed) when no time is given

v^2= u^2 + 2as

Newton first law (Law of Interia)

A body remains at rest or continues at a uniformed velocity provided that no external force acts on it

Newtons Second Law

The acceleration of a body is proportional to and in the same direction as the resultant force acting on it

resultant force (F)

mass(Kg) x acceleration (m/s^2)

Newtons Third Law

For every action there is an qual and opposite reaction

Momentum formula

mass x velocity

The law of conservation of momentum states that...

When two or more objects interact the total momentum before the interaction is equal to the total momentum after the collision provided that no external force acts on the objects

Work formula

force x dispacement (distance)

Energy definition

The ability to do work

Gravitational potential energy definition

this is the energy that a body has due to its position in the gravitational field

Gravitational potential energy formula (change in EP)

mass x gravitational field strength x change in height

kinetic energy definition

this is energy that a body as becuase of motion

Kinetic energy formula

1/2m x v^2

effciency formula

useful output

--------------------- x 100

input

Pressure definition (Measured in Pascal [P])

This can be defined as force per unit area

pressure formula

force/area

pressure in fluids formula

desity of fluid x change in height x gravitational field strength

Archimedes principle states that

when an objects is completely or partially immersed in a fluid it experiences an upthrust that is equal to the displaced fluid

apparent weight formula

read weight - upthrust

Upthrust formula

desity of fluid x volume of displaced fluid x accel due to gravity

Principle of floatation states that

a floating body displaces its own weight of fluid

Temperature definition

This is a measure of the average kinetic energy of molecules

Brownian motion definition

the eratica and radom movements of microscropic perticles in fluids as the bounce off surrounding molecules

liquid in glass thermometer property

volume of liquid

resistance thermometer property

electrical resistance of a metal

constant volume gas thermometer property

pressure of gas at constant volume

thermocouple thermometer

Electrical potential difference between two metals in contact

The three phases of matter are

solid, liquid and gas

Boyle's Law states that

For a fixed mass of gas at a constant temperature the pressure of the gas is inversley proportional to the volume of the gas

The pressure law states that

For a fixes mass of gas at a constant volume the pressure of the gas is directly proportional to the aboslute temperature of the gas

Charles law states that

for a fixed mass of gas at a constant pressure that volume of the gas is directly proportional to the absolute temperature of the gas

Thermocouple thermometer

Laboratory themometer

Clinical thermometer