Edexcel International GCSE Physics Revision Guide - Forces, Motion, Energy, Waves, Electricity, Magnetism, Radioactivity, Astrophysics

Flashcards covering key concepts from the Edexcel International GCSE Physics Revision Guide, including forces, motion, energy, waves, electricity, magnetism, radioactivity, and astrophysics.

Speed

How fast you're going with no regard to direction.

Velocity

How fast you're going with the direction specified.

Average Speed

Distance / Time

Acceleration

How quickly velocity is changing, either in speed or direction, measured in m/s^2.

Acceleration Formula 1

Change in Velocity / Time Taken

Acceleration Formula 2

Final Velocity^2 = Initial Velocity^2 + (2 x Acceleration x Distance)

Distance-Time Graph

A graph that shows how far something has travelled over time; the gradient represents speed, flat sections indicate the object is stopped, curves represent acceleration and deceleration.

Velocity-Time Graph

A graph that plots an object's velocity over time; flat sections represent steady speed, the gradient represents acceleration or deceleration, and the area under the graph equals the distance travelled.

Gravity

The force of attraction between all masses, which makes objects accelerate towards the ground, gives everything a weight, and keeps planets in orbit.

Mass

The amount of 'stuff' in an object, measured in kilograms (kg).

Weight

The force of gravity pulling on an object, measured in newtons (N).

Weight Formula

Weight = Mass x Gravitational Field Strength (W = m x g)

Force

A push or pull, including gravity, reaction force, electrostatic force, thrust, drag, lift, and tension.

Friction

A force that opposes motion, occurring between solid surfaces (gripping or sliding) and from fluids (liquids or gases).

Newton's First Law of Motion

When the forces on an object are balanced, so it stays still or continues at the same velocity.

Newton's Second Law of Motion

An unbalanced force will cause an object to accelerate in that direction.

Newton's Second Law Formula

Force = Mass x Acceleration (F = ma)

Newton's Third Law of Motion

For every action, there is an equal and opposite reaction.

Vector Quantity

A quantity with both size and direction (e.g., force, velocity, acceleration, momentum).

Scalar Quantity

A quantity with only size, not direction (e.g., mass, temperature, time, length).

Terminal Velocity

The maximum velocity reached by a falling object when the resistance force equals the accelerating force.

Natural Length

The length of an unstretched metal wire.

Hooke's Law

A force which can cause an object to change shape.

Hooke's Law Definition

Extension of a stretched wire is proportional to the load or force.

Elastic Limit

The point beyond which a material is permanently stretched and will not return to its original length.

Stopping Distance

The distance covered in the time between a driver spotting a hazard and the car coming to a complete stop.

Thinking Distance

The distance travelled in the time between the driver noticing the hazard and applying the brakes.

Braking Distance

The distance the car travels during its deceleration while the brakes are being applied.

Momentum

Mass x Velocity, a vector quantity measured in kg m/s.

force

change in momentum / time

Moment

Force(N) x Perpendicular Distance(m) from line of action to the pivot

Principle of Moments

If an object is balanced, the Total Anticlockwise Moments equal the Total Clockwise Moments.

Current

rate of flow of charge round the circuit (A)

Voltage

electrical pressure (V)

Resistance

anything in the circuit which slows the flow down. (Ω)

V=IR

voltage = current x resistance

LEDs

light-emitting diodes

LDR

light-dependent resistor

thermistor

temperature-dependent resistor

Series Circuit

When components are connected in a line, end to end, between the +ve and -ve power supply

Parallel Circuit

Is when each component is separately connected to the +ve and -ve of the supply

Charge through a Circuit

It depends on current and time where Q = I x T

Energy transfer

Is transferred to or from a charge as it passes through a voltage

Three wires in a Plug

earth, live and neutral

Earthing and Fuses Prevent Fires and Shocks

Isolate the whole appliance, making it impossible to get an electric shock from the case

Circuit Breakers

Protects the circuit from damage if too much current flows.

Electrical Power

The rate at which an appliance transfers energy.

Power Formula

power = current × voltage

Static

Electrostatic charge which cannot move

Electrostatic forces

Two things with opposite electric charges are attracted to each other

Conductors

conduct charge easily

Insulators

don't conduct charge very well

Electrons

materials can be charged by friction

Waves

longitudinal or transverse

Wavelength

distance from one peak to the next.(m)

Frequency

number of complete waves per second passing a certain point. (Hz)

Amplitude

height of the wave from rest to crest (m)

Speed

how fast the wave goes (v, m/s)

Wave Equation

Speed = Frequency x Wavelength (v = f λ)

TRANSVERSE

vibrations are at 90° to the direction energy is transferred

LONGITUDINAL

vibrations are along the same direction as the wave transfers energy

Wavefronts

are imaginary planes that cut across all the waves, connecting the points on adjacent waves which are vibrating together

long or short

Doppler Effect

Electromagnetic waves

radio, microwave, infrared, visible light, ultraviolet, X-rays and gamma rays.

Order Of Colors: longest to shortest

red, orange, yellow, green, blue, indigo, violet

Uses of EM Waves

light, heating or communications.

Damage From EM Radiation

cause of cancerous changes in living cells e.g. gamma rays can cause cancer

Reflection

wave bounces off an even surface

Refract

wave slows down or speeds up at a boundary between two materials.

LAW OF REFLECTION

Angle of incidence = Angle of reflection

refractive index

the speed of light in a vacuum, c / speed of light in that material, v

Snell's Law

refractive index, n = sin i/sin

Criticality

Light going from a higher refractive index to a lower speeds up = bends away from normal angle.

Critical Angle

occurs when the angle of incidence is equal to a critical angle

conservation of energy

energy can be stored, transferred between stores, and dissipated - but it can never be created or destroyed. The total energy of a closed system has no net change.

different stores of energy

kinetic, thermal, chemical, gravitational potential, elastic potential, electrostatic, magnetic, nuclear

efficiency

efficiency = useful energy output / total energy output x 100%

total energy INPUT

the amount of energy supplied to a machine

useful energy OUTPUT

how much useful energy the machine delivers

Heating

energy is transferred from a hotter object to a colder object. (Heating a pan of water on a hob)

Infrared radiation

heat radiation. (Electrical heaters radiate IR to keep us warm)

Convection

hotter region to the cooler region - and transfer energy as they do. (Immersion heaters in kettles)

Conduction

Occurs mainly in solids the process where vibrating particles transfer energy from their kinetic energy store to the kinetic energy stores of neigh- bouring particles.

Work done

work done = Force x Distance moved

Power

the rate at which energy is transferred

Power Formula

Power (watts) = Work done(J) / Time Taken(s)

Kinetic Energy Formula

KE = ½ x mass X (speed)

Gravitational Potential Energy Formula

gpe = mass X gravitational field strength x height

non-renewable sources of energy

coal, oil, natural gas and nuclear

Wind power

wind power involves putting lots of wind turbines up in exposed places

Geothermal Power

Water is pumped in pipes down to the hot rocks and forced back up due to pressure to turn a turbine which drives a generator.

Solar cells

solar cells (photocells) use energy from the Sun to directly generate electricity

tidal barrages

Water is transferred from the kinetic energy stores of the water to the kinetic energy store of the turbine, and used to generate electricity

Hydroelectricity

Rainwater is caught and allowed out through turbines, transferring energy from the gravitational potential energy store of the water

Mass Density

Density (p)= mass (m) / volume (v)

Pressure

Pressure = force / area

Pressure difference

Pressure difference = height x density × gravitational field strength

Melting or Boiling a Substance

Energy is used for breaking bonds between particles rather than raising the temperature. So the substance stays at a constant temperature.

Evaporation

Molecules near the surface of a liquid can escape and become gas particles if…

Absolute Zero

The particles have as little energy in their kinetic stores as it's possible to get.