GCSE Edexcel (9-1) Combined Science Physics Paper 1

What is a scalar quantity?

One that has magnitude (size) only.

What is a vector quantity?

One that has magnitude (size) and direction.

These are examples of scalar quantaties:

Distance, speed, mass, energy.

These are examples of vector quantaties:

Displacement, velocity, acceleration, force, weight, momentum.

What is velocity?

Speed in a given direction.

What is the equation for (average) speed?

Distance travelled ÷ time taken

What are the units of speed?

m/s

What is the equation for distance travelled?

average speed x time taken

How do you find the speed from a distance time graph?

Calculate the gradiant of the distance time graph.

What are the units of acceleration?

m/s/s or m/s squared

How do you find the acceleration from a speed time graph?

Calculate the gradiant of the speed time graph.

How do you find the distance travelled from a speed time graph?

Calculate the area under the graph.

What does a horizontal line on a speed time graph show?

Constant speed.

What does a horizontal line on a distance time graph show?

No movement

What does a steep line on a speed time graph show?

Fast acceleration.

What does a steep line on a distance time graph show?

Fast speed.

What is a light gate?

An electronic timer that measures the time taken for an IR beam to be broken.

What is the advantage of a light gate?

More accurate as does not involve human reaction times.

What is typical walking speed?

1.5 m/s

What is a typical running speed?

5 m/s

What is a typical cycling speed?

6 m/s

What is a typical driving speed in built up areas?

10 m/s

What is a typical driving speed on motorways?

30 m/s

How big is the acceleration due to gravity on Earth?

10 m/s2

What is Newton's first law?

If the resultant force on an object is zero then its acceleration is zero.

What would happen to the movement of an object if the resultant force is zero?

Its movement would remain constant

What would happen to the movement of an object if the resultant force is not zero?

It would accelerate in the direction of the resultant force.

What is the equation for Newton's second law?

Force = mass x acceleration

What is the equation for weight?

Weight = mass x acceleration due to gravity

What are the units of weight?

Newton

How would you measure weight?

Use a force meter.

What is Newton's third law?

For every force there is an equal and opposite reaction.

What is a typical value for a human's reaction time?

0.1 - 0.3 second

What is stopping distance for a vehicle made up of?

Stopping distance = Thinking distance + Braking distance

What factors affect the thinking distance of a driver?

Speed, reaction time.

What factors affect the braking distance of a driver?

Speed, mass of the vehicle, state of the brakes, state of the road, amount of friction between road and tyres.

What might affect a driver's reaction time?

Drugs (alcohol, illegal drugs and medication) and distractions (mobile phone, talking, doing something else.)

Why are large decelerations dangerous?

They put a large force on the object / person.

What is a typical wind speed?

5-20 m/s

What is a typical speed of sound?

330 m/s

What is Newton's third law?

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

gravitational potential energy =

mass x gravitational field strength x change in height

kinetic energy =

1/2 x Mass x V^2

conservation of energy means that ...

... energy cannot be created or destroyed, only transferred from one kind to another

an object thrown upwards transfers ...

... kinetic energy to gravitational potential energy

a moving object hitting an obstacle transfers ...

... kinetic energy to thermal energy and sound

an object being accelerated by a constant force ...

... has increasing kinetic energy

a vehicle slowing down transfers ...

... kinetic energy to thermal energy

a kettle heating water transfers ...

... electrical energy to thermal energy

when there are energy transfers in a closed system ...

... there is no net change to the total energy of the system

mechanical processes become wasteful as they transfer ...

... thermal energy to the surroundings

we can reduce unwanted energy transfers in mechanical systems by ...

... lubricating the surfaces to reduce friction

we can reduce unwanted thermal energy transfers from hot objects by ...

... using thermal insulation

when energy is dissipated to the surroundings ...

... it is harder to use and so stored in a less useful way

if the walls of a building are thicker ...

... the rate of cooling will be reduced

if the walls of a building are made of a material with a higher thermal conductivity ...

... the rate of cooling will be increased

efficiency =

useful energy / total energy

fossil fuels

an energy source formed from the remains of living organisms millions of years ago producing carbon dioxide when burned

nuclear fuel

uranium used as a non-renewable energy source

bio-fuel

a renewable energy source formed from the breakdown of organic material

amplitude

Height of a wave

electromagnetic waves

A group of waves that all travel at the same speed in a vacuum, and are all transverse.

frequency

The number of vibrations (or the number of waves) per second.

hertz (Hz)

The unit for frequency. One hertz is one wave per second.

longitudinal wave

A wave where the particles vibrate in the same direction as the wave is travelling.

medium

Any substance through which something travels.

period

The time taken for one complete wave to pass a point. It is measured in seconds.

seismic waves

Vibrations in the rocks of the Earth caused by earthquakes or explosions.

sound waves

Vibrations in the particles of a solid, liquid or gas, which are detected by our ears and 'heard' as sounds.

transverse wave

A wave where the vibrations are at right angles to the direction the wave is travelling.

velocity

The speed of an object in a particular direction. Usually measured in metres per second (m/s).

wave

A way of transferring energy or information. Many waves travel when particles pass on vibrations.

wavelength

The distance between a point on one wave and the same point on the next wave.

normal

An imaginary line at right angles to a surface where a ray of light hits it.

refraction

The change in direction when waves go from one medium to another.

infrared (IR)

Electromagnetic radiation that has a longer wavelength than visible light but shorter than microwaves. We can feel infrared radiation as warmth.

ultraviolet (UV)

Electromagnetic radiation that has a shorter wavelength than visible light but a longer wavelength than X-rays.

vacuum

A place where there is no matter at all.

visible light

Electromagnetic waves that can be detected by the human eye.

angle of refraction

The angle between the normal and a ray of light that has been refracted.

gamma rays

Electromagnetic radiation with the shortest wavelengths and highest frequencies.

microwaves

Electromagnetic radiation with a longer wavelength than infrared radiation but a shorter wavelength than radio waves.

radio waves

Electromagnetic radiation with the longest wavelengths and lowest frequencies.

X-rays

Electromagnetic radiation that has a shorter wavelength than ultraviolet radiation but a longer wavelength than gamma rays.

radiotherapy

Cancer treatment in which a patient is given gamma radiation to kill the cancer cells.

How do you remember electromagnetic spectrum names?

Real Men In Violet Underwear are eXtremely Gorgeous

alpha particle

A particle made of two protons and two neutrons, emitted as ionising radiation from some radioactive isotopes.

atomic number

the number of protons in the nucleus of an atom

isotope

Atoms of an element with the same number of protons (atomic number) but different mass numbers due to different numbers of neutrons.

mass number

the total number of protons and neutrons in the nucleus of an atom

background radiation

Ionising radiation that is around us all the time from a number of sources. Some background radiation is naturally occurring, but some comes from human activities.

count rate

The number of alpha or beta particles or gamma rays detected by a Geiger-Müller tube in a certain time.

Geiger-Müller (GM) tube

A device that can detect ionising radiation and is used to measure the activity of a radioactive source.

alpha particle

A particle made of two protons and two neutrons, emitted as ionising radiation from some radioactive isotopes.

beta particle

A particle of radiation emitted from the nucleus of a radioactive atom when it decays. It is an electron.

decay (radioactive)

When an unstable nucleus changes by giving out ionising radiation to become more stable.

positron

The anti-particle of an electron, having the same mass but opposite charge. Positron emission is a type of beta decay.

nuclear equation

An equation representing a change in an atomic nucleus due to radioactive decay. The atomic numbers and mass numbers must balance.

becquerel (Bq)

The units for the activity of a radioactive object. One becquerel is one radioactive decay per second.

half-life

The average time taken for half of the radioactive nuclei in a sample of radioactive material to have decayed. It is also the time taken for the activity of a source to fall to half its value.