Year 9 Physics End of Term 3 Assessment Revision

Practice flashcards covering vocabulary and core concepts for Year 9 Physics Revision, including motion, energy transfers, thermal physics, and states of matter.

Speed

The distance travelled per unit time.

Velocity

The speed of an object in a given direction.

Acceleration

The change in velocity per unit time, calculated using the formula $a = \frac{v-u}{t}$.

Acceleration of free fall

A constant acceleration experienced by objects near to the Earth.

Distance-time graph gradient

The gradient of the line represents the velocity.

Velocity-time graph gradient

The gradient of the line represents the acceleration.

Velocity-time graph area

The area under the line represents the distance travelled.

Kinetic energy store

The energy store associated with moving objects.

Gravitational potential store

The energy store gained by objects when they are lifted through a gravitational field.

Elastic potential store

The energy store in objects that are stretched, squashed, or bent.

Magnetic store

The energy store involving magnetic materials interacting with each other.

Electrostatic store

The energy store involving objects with charge, such as electrons and protons, interacting with one another.

Chemical store

The energy store where chemical reactions transfer energy into or away from a substance.

Nuclear store

The energy store from which atomic nuclei release energy during nuclear reactions.

Thermal store

The energy store all objects have; the hotter the object, the more energy it has in this store.

Efficiency

The ratio of the useful energy output to the total energy supplied, often expressed as a percentage: $\text{efficiency} = \frac{\text{useful energy output}}{\text{total energy input}} \times 100\%$.

Sankey diagrams

Visual representations of energy transfers where the width of arrows shows the proportions of energy transfers taking place.

Conduction

The transfer of thermal energy in solids and liquids by the vibration of particles.

Thermal insulators

Poor conductors, usually non-metals, that transfer heat slowly and are used to reduce unwanted energy transfer.

Convection

The transfer of thermal energy in fluids (liquids and gases) occurring when molecules move from an area of high to low thermal energy.

Radiation (Thermal)

The transfer of thermal energy by infrared radiation, which is part of the electromagnetic spectrum and does not require a medium.

Density

The mass per unit volume of a substance, measured in $kg/m^3$, calculated as $\rho = \frac{m}{V}$.

Pressure

The force per unit area, measured in Pascals ($Pa$), calculated as $P = \frac{F}{A}$.

Pressure in a liquid

The pressure beneath a liquid surface that increases with depth, density, and gravitational field strength, given by $p = h \times \rho \times g$.

Specific heat capacity

The amount of energy required to raise the temperature of $1\,kg$ of a substance by $1^{\circ}C$, measured in $J/kg^{\circ}C$.

Absolute zero

The temperature at which the pressure of a gas is zero, equivalent to $-273^{\circ}C$ or $0\,K$.

Kelvin scale

A temperature scale where an increment of one Kelvin is equal to an increment of one degree Celsius, calculated as $\text{temperature in Kelvin} = \text{temperature in degrees Celsius} + 273$.

Boyle's Law

For a gas at fixed mass and temperature, the pressure multiplied by the volume is constant: $P_1 \times V_1 = P_2 \times V_2$.

Evaporation

The escape of higher-energy molecules from the surface of a liquid, which lowers the average kinetic energy and temperature of the remaining liquid.

Boiling

A change of state occurring throughout a liquid only at its boiling point, where molecules gain enough energy to break bonds and become a gas.