AQA Physics GCSE Paper 2

These flashcards cover essential definitions and concepts related to AQA Physics GCSE Topic 5: Forces.

What is Acceleration in physics?

The rate of change of velocity.

What is the definition of Atmosphere?

The thin layer of air surrounding the Earth, which gets less dense with increasing altitude.

What is Braking Distance?

The distance a vehicle travels under the braking force, affected by road and weather conditions as well as the vehicle's condition.

Define Centre of Mass.

The single point through which the weight of the object can be said to act.

What happens during Changes of Momentum?

When a force acts on a moving object, or one that has the ability to move, a change of momentum will occur.

State the Conservation of Momentum principle.

The total momentum of a system before an event is always equal to the total momentum of the system after the event.

What are Contact Forces?

Forces that occur when objects are physically touching.

Define Displacement.

A measure of how far an object moves in a given direction; the straight line between the starting and finishing points.

How is Distance defined in physics?

A measure of how far an object moves that does not depend on direction.

What is Elastic Deformation?

Non-permanent deformation which allows the object to return to its original shape when the deforming forces are removed.

What is the Elastic Limit?

The force beyond which an object will no longer deform elastically and will instead deform plastically.

Define Elastic Potential Energy.

The energy stored in a spring when stretched or compressed, equal to the work done as long as the object does not plastically deform.

What does Equilibrium mean in physics?

An object is in equilibrium if the resultant force and resultant moment are both equal to zero.

What does it mean for an object to Float?

An object will float if the volume of liquid it displaces has a greater weight than that of the object itself.

What is Inertia?

The tendency of an object to remain in its same state of uniform motion or rest.

Define Inertial Mass.

A measure of how hard it is to change an object’s velocity, defined as the ratio of force over acceleration.

What is the Limit of Proportionality?

The point beyond which the extension of an elastic object is no longer directly proportional to the force applied to it.

What is Momentum?

The product of an object’s mass and velocity.

What does Newton's First Law state?

Objects will remain at rest, or move with a constant velocity unless acted on by a resultant force

What is Newton's Second Law?

An object’s acceleration is directly proportional to the force applied to it and inversely proportional to its mass.

State Newton's Third Law.

The forces that two objects exert on each other when they interact are equal and opposite.

What are Non-Contact Forces?

Forces that occur when objects are physically separated.

What is Plastic Deformation?

Permanent deformation where the object no longer returns to its original shape when the deforming forces are removed.

What is meant by Resultant Force?

A resultant force is a single force that describes all of the forces operating on a body. It is sometimes called the net force

Define Scalar Quantities.

Quantities that only have a magnitude, not a direction.

What occurs when an object Sinks?

An object will sink if the volume of liquid it displaces has a lower weight than that of the object itself.

What is Speed?

A scalar quantity that is a measure of the rate of increase of distance.

Define Spring Constant.

A measure of spring’s stiffness, constant of proportionality for a spring’s extension.

What is Stopping Distance?

The sum of the thinking and braking distances.

Define Thinking Distance.

The distance a vehicle travels during the driver’s reaction time. can be affected by speed, distractions, alcohol, tiredness.

What is Upthrust?

The upward force acting on an object in a fluid, due to greater pressure below it than above it.

What are Vector Quantities?

Quantities that have both magnitude and direction, represented by an arrow.

What is Velocity?

A vector quantity that measures the rate of change of displacement.

Define Weight in physics.

The force acting on an object due to gravity, equal to the product of the object’s mass and gravitational field strength.

What is Work Done?

Work is done on an object when a force causes it to move through a distance. / it is equal to the transfer of kinetic energy

What’s Hooke’s Law?

‘The extension of an elastic object is directly proportional to the force applied, up to the limit of proportionality’

What’s the principle of moments?

If an object is balanced, the total clockwise moment about a pivot equals the total anticlockwise moment about that pivot

What’s pressure?

The concentration of a force or the force per unit area

How do car safety features reduce injury?

1. The safety feature increases the time taken/distance to stop (or for the decrease in momentum)

2. This decreases the rate of change of momentum

3. This reduces the force on the object

What’s terminal velocity?

Terminal velocity is the maximum velocity that an object can attain when it is falling through a fluid, such as air or water

Amplitude

The maximum displacement of a wave from its undisturbed (equilibrium)

position.

Angle of Incidence

The angle between the incident ray and normal.

Angle of Reflection

The angle between the reflected ray and normal.

*Constant Temperature

A body remains at a constant temperature if it is absorbing radiation at the same rate that it is emitting it.

absorbing radiation at the same rate that it is emitting it.

Convex Lens

A lens that brings parallel rays to focus at the principal focus.The image formed can be either real or virtual.

Diffuse Reflection

Reflection from a rough surface that results in scattering.

*Echo Sounding

A technique that uses high frequency sound waves to detect objects in deep water and to measure the depth of water.

Electromagnetic Waves

Transverse waves that transfer energy from the source of the

waves, to an absorber. They form a continuous spectrum of different frequencies and all

travel at the same speed in a vacuum.

Focal Length

The distance between the centre of a lens and its principal focus

Frequency

The number of waves passing a given point in a second. It is the inverse of the

wave’s period.

*Human Hearing

Humans can hear sounds in the frequency range of 20Hz to 20kHz.

Infrared Radiation

A type of radiation that all objects emit and absorb.

is, the greater the infrared radiation it emits in a given time. Infrared

Used for cooking food,

electrical heaters and infrared imaging.

Ionising Radiation

Radiation that can cause the mutation of genes and cause cancer. Xrays and gamma rays are both forms of ionising radiation.

Lens

An object that forms an image through the refraction of light.

Longitudinal Waves

Waves with oscillations that are parallel to the direction of travel/energy transfer.

Magnification

The ratio of the image height over the object height for a lens. Since it is a ratio, it has no units.

Microwaves

Used for satellite communications and for cooking food.

Normal

The normal is an imaginary reference line that is constructed perpendicular to a boundary at the point that the wave intercepts it.

*P-Waves

Longitudinal, seismic waves that travel at different speeds through solids and liquids.

*Perfect Black Body

An object that absorbs all radiation incident on it and does not reflect

or transmit any type of radiation.

Period

The time it takes for one complete wave to pass a given point. It is the inverse of

frequency.

Radiation Dose

A measure of the risk of harm to the body as a result of radiation

exposure.

Radio Waves

Used for television and radio signals. They can be produced by oscillations in electrical circuits

electrical circuits.

*Reflection

Reflection is when a wave bounces off a boundary.

always equals the angle of reflection

*S-Waves

Transverse, seismic waves that cannot travel through liquids.

Waves

Waves that are produced by earthquakes.

*Sound Waves

The longitudinal waves responsible for sound. In solids, sound waves are transmitted by the vibrations of the solid’s particles.

are transmitted by the vibrations of the solid’s particles.

Specular Reflection

Reflection from a smooth surface, in a single direction. Transverse

Transverse Waves

Waves with oscillations that are perpendicular to the direction of travel/energy transfer.

of travel/energy transfer.

*Ultrasound Scanning

A technique that involves ultrasound waves being transmitted and then partially reflected at a boundary before being detected by a detector. The time between transmission and detection can be used to calculate distances, and build up an image.

and then partially reflected at a boundary before being detected by a detector. The

time between transmission and detection can be used to calculate distances, and

build up an image.

*Ultrasound Waves

Waves that have a frequency higher than the upper limit of

human hearing (20kHz).

Ultraviolet

Used in energy efficient lamps and for sun tanning.

Visible Light

The only type of electromagnetic radiation that our eyes can detect.

It is used for fibre optic communications.

Wave Speed

The speed at which energy is transferred through the medium. It is equal to the product of the wave’s wavelength and frequency.

the product of the wave’s wavelength and frequency.

Wavelength

The distance from a point on one wave to the same point on the adjacent

wave (ie. peak to peak or trough to trough).

Alternator

A device that makes use of the generator effect to generate alternating

current.