A comprehensive guide for IGCSE Edexcel students that contains all the knowledge you need to know for students aiming to achieve a grade 8/9 in Physics papers 1 and 2. These notes promote active recall for the memorization part of Physics and some questions are also specifically tailored to match t...
Unit 1: Forces and Motion:
What does the gradient of a line in a distance- It tells us its speed.
time graph tell us about the moving object?
What is displacement? Distance travelled in a particular direction from
a specified point.
What is a vector? Something that has a magnitude and a specific
direction.
What is the equation for acceleration? v−u
a=
t
What does SUVAT stand for? S = displacement
U = initial velocity
V = final velocity
A = acceleration
T = time
What does a negative acceleration equate to? Deceleration
What does the area under a velocity-time graph The displacement.
tell us?
What is the equation to calculate v 2? v 2=u2 +2 as
What kind of measurement is a force? A vector
What are the names of forces? Weight
Normal reaction force
Friction
Tension
Drag
Air resistance
Thrust
Lift
What is important to consider when drawing The size of the arrows that indicate force must
forces diagrams? be proportional to the force.
What will one newton do to a mass of one It will make it accelerate at one metre per
kilogram? second squared.
What is a newton measuring? Force
Can upthrust act on objects in liquids? Yes
When you comb your hair why does some of Electrostatic forces.
the air stick to the comb?
If an object is stationary then what can this tell They are balanced?
us about the forces acting on it?
What happens if forces are unbalanced? The object is in accelerated motion.
If a car is moving what force is allowing it to Thrust from the engine.
move?
What happens when friction forces balance The car moves at a constant speed.
with the thrust from a car engine?
What do springs do? Change length when a force acts on the them
and return to their original length when the
force is removed provided that they are not
stretched beyond the elastic limit.
What is Hooke’s law? Force = -1 X spring constant X spring stretch
Do elastic bands obey Hooke’s law? No
What is the equation that links force, mass and F=m× a
acceleration?
,What unit is mass always measured in when Kilograms
reading equations?
How would you calculate the force a person Mass X negative acceleration
experiences when they crash a car?
What is the stopping distance the sum of? Thinking distance and braking distance?
What factors influence thinking distance? Visibility of the road (fog).
If the driver is tired or under the
influence of drugs and alcohol.
What factors influence braking distance? Weight of the car
Conditions of the road
Condition of the tires.
How is weight calculated? m× g (mass × gravitational field strength)
What is gravitational field strength of the Earth? 10N/kg
What is a drag coefficient? A measure of how easily an object can move
through a fluid.
Describe the process that occurs when a When they just jump their starting
parachutist jumps from a plane: velocity is 0m/s and there is no drag.
The resulting downward force is just
weight and therefore they accelerate
towards Earth.
When the person accelerates the drag
force will gradually increase so that the
acceleration of the person decreases.
The drag force will eventually increase
to the point where it balances the
weight force and the person is now at
terminal velocity.
When the parachute opens there is a
sudden increase in drag force. At this
velocity the drag force is greater than
the weight of the skydiver so the
parachutist decelerates.
As the parachutist slows down the size
of the drag force decreases and a new
terminal velocity is reached.
How is momentum calculated? p=m× v
What is the relationship between momentum ∆p
F=
and force? t
Is momentum conserved? Yes
What is the purpose of a crumple zone? They collapse during a collision and increase the
time during which the car is decelerating to
reduce the force acting on the passenger.
What is Newton’s third law? For every action there is an equal and opposite
reaction.
What is a pivot? The point around which something can turn or
rotate.
What is the moment of a force measured in? Nm
How is the moment of a force calculated? Force X perpendicular distance from pivot.
What is the centre of gravity/mass? The point where the whole weight of an object
appears to act.
,Unit 2: Electricity:
What is the purpose of fuses and circuit They shut off the electricity in a circuit if the
breakers? current in them becomes too large.
What are the three wires that a ring main A live wire, neutral wire and the earth wire.
circuit consists of?
What does the live wire do? It provides a path along which the electrical
energy from the power station travels.
What does the neutral wire do? It completes the circuit.
What does the earth wire do? It has no current in it and is just there to protect
you if an appliance develops a fault as it
provides a path for current to escape without
passing through the user.
What is roughly the voltage of the mains 220V
electricity that is supplied to homes in the UK?
What is an insulator? A material through which it is very difficult or
impossible for electricity to flow.
Why do connections to circuits use three brass Brass is a good conductor of electricity.
pins?
What is a safety feature of a plug? It is insulated with a plastic casing.
What does a fuse consist of? A cartridge with a thin piece of wire made from
a metal with a low melting point.
How does a fuse work? If there is too large a current in the
circuit the fuse wire melts and blows.
The circuit is now incomplete so there
is no current.
This prevents you getting a shock and
reduces the possibility of an electrical
fire.
Once the fault causing the increase in
current has been corrected, the blown
fuse must be replaced with a new one
in order for the appliance to be used
again.
What is a benefit of using a circuit breaker of If there is too large a current in the circuit the
trip switch instead of a fuse? switch opens and the circuit is incomplete.
Once the fault has been corrected the switch
can be reset and there is no need for the switch
of circuit breaker to be replaced like with a fuse.
, What is double insulation? When all the electrical parts of an appliance are
insulated most commonly be a plastic insulator
so that they cannot be touched by the user.
To appliances with metal casings need an Earth Yes, so that the earth wire can provide a low-
wire? resistance path for the current if the live wire
becomes damaged or breaks and comes into
contact with the casing.
To appliances with double insulation require an No, they use a two-wire flex.
Earth wire?
Why should switches always be placed in the If it is placed in the neutral wire then electrical
live wire? energy can still enter a faulty appliance and give
the user an electric shock. However, if it is
placed in the live wire then no electrical energy
can enter the appliance.
What are heating elements? Coils of wires used to transfer electrical energy
to heat energy.
Why do we want wires with a high resistance in When a current passes through them we want
appliances such as kettles or toasters? energy to be transferred and the element heats
up.
What are examples of appliances that use the Bulbs (the filament glows when it is
heating effect of electricity? hot).
Kettles.
Dishwashers.
Electric cookers.
Between a 50W and 70W bulb which bulb will The 70W bulb as it transfers 70J of electrical
be brighter and why? energy every second.
What power measured in? Joules per second or Watts(W)
What is the equation linking power with current Power = current X voltage
and voltage? P=I ×V
What is current measured in? amps
If an appliance has a 4A current what fuse 5A fuse
should be used?
How would you calculate the total energy E=P× t
transferred by an appliance in a given time? E=I ×V ×t
What type of current comes from the mains? Alternating current
What is the difference between an a.c. and d.c. Current in an a.c. supply alternates between
supply? positive and negative voltage in the form of a
wave, whilst d.c. voltage stays positive and
doesn’t not voltage.
What kind of voltage comes from a battery or Direct voltage
cell?
What is electric current? The flow of charge.
What are charges carried by? Electrons.
Why are metals good conductors? Electrons flow easily through all metals.
Why is plastic a good insulator? Electrons don’t flow easily through plastic.
In terms of the movement of electrons what More electrons flow in the direction away from
happens when a battery is connected across a the negative terminal and towards the positive
conductor? terminal and there is now a net flow of charge.
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