physics for science exam

Define physical quantities 

• A physical quantity is a measurement of something. 

• It should have a numerical value to show its size and an appropriate unit 

State physical quantity symbols and measurement units 

Physical Quantity	Standard Unit	Unit Abbreviation
Length	meters	m
Mass	kilograms	kg
Time	seconds	s
Electric Current	amperes	A
Temperature	Kelvin	K
Volume	Liters	L

 

Define Scalar and Vector 

• A scalar quantity is a quantity that has size but not direction. 

• A vector quantity is a quantity that has size and direction. 

Define Displacement and Distance 

Distance: 

• How far an object travels in total. 

• A scalar quantity measured in meters. 

Displacement 

• The straight line distance between the starting and finishing points. 

• A vector quantity and is measured in meters with a direction.

Define speed and velocity 

The terms speed and velocity both relate to how fast something is occurring. 

Speed: 

• Speed is Scalar (it only has size) 

• The change of distance in a given time. 

Velocity: 

• Velocity is vector (it has size and direction) 

• The change of displacement in a given time with a direction. 

Convert between km h-1 to ms-1 

• Km/h - m/s = divide by 3.6 

• m/s - km/h = times by 3.6 

Define Acceleration 

The rate at which an object’s velocity changes over time. 

What is the si unit for acceleration 

m/s squared 

Define Neuton’s three laws of motion 

Law of inertia 

F=ma 

Law of action//reaction 

Law of inertia 

• An object at rest tends to remain at rest 

• An object in motion tends to remain in motion at constant speed along a straight line path. 

F=ma 

• When a force acts on an object the object will accelerate 

• The acceleration is proportional to the net force and inversely proportional to the mass 

• i.e. more mass = less acceleration 

• Force = mass times acceleration 

Law of action//reaction 

• Whenever one object exerts a force on a second object, the second object exerts an equal and opposite reaction on the first 

Kinetic energy examples

• motion

• light

• heat

• electrical

• sound

Potential energy examples

• elastic

• gravitational

• chemical

• static

Law of Conservation of Energy

energy can’t be created or destroyed; only transformed or transferred

Energy transfer

the flow of energy from one object to another

Eg. if you stand in front of the heater the heat energy is transferred from the heater to you

Energy Transformation

the conversion of one form of energy into another form of energy

Eg. an mp3 player transforms chemical energy from the battery into sound energy

What is the main cause of wasted energy?

Friction as it creates heat energy.