Unit 1: Forces and Motion Specification Checklist

Key vocabulary, definitions, and equations covering units, movement, position, forces, momentum, and moments from the Unit 1 Forces and Motion specification checklist.

Average speed

A measure of motion defined by the relationship $\text{average speed} = \frac{\text{distance moved}}{\text{time taken}}$, typically measured in metres per second ($\text{m/s}$).

Acceleration

The rate of change of velocity with respect to time, calculated using $\text{acceleration} = \frac{\text{change in velocity}}{\text{time taken}}$ ($a = \frac{v - u}{t}$), measured in $\text{m/s}^2$.

Gradient of a velocity-time graph

The steepness or slope of a velocity-time graph, which represents the acceleration of an object.

Area under a velocity-time graph

The area bounded between a velocity-time graph and the time axis, which represents the distance travelled by the object.

Uniform acceleration equation

The relationship relating final speed, initial speed, acceleration, and distance moved: $(\text{final speed})^2 = (\text{initial speed})^2 + (2 \times \text{acceleration} \times \text{distance moved})$, written algebraically as $v^2 = u^2 + 2as$.

Vector quantity

A physical quantity that differs from a scalar quantity because it possesses both magnitude and direction (for example, force or velocity).

Friction

A force that opposes the motion of an object.

Unbalanced force relationship

The fundamental relationship linking unbalanced force, mass, and acceleration: $\text{Force} = \text{mass} \times \text{acceleration}$ ($F = m \times a$).

Weight

The gravitational force acting on an object, determined by $\text{Weight} = \text{mass} \times \text{gravitational field strength}$ ($W = m \times g$).

Stopping distance

The total distance a vehicle travels before coming to rest, calculated as the sum of the thinking distance and the braking distance.

Terminal velocity

The constant maximum velocity reached by a falling object when the resistive forces opposing its motion equal the gravitational force acting on it.

Hooke's law

The physical principle associated with the initial linear region of a force-extension graph.

Elastic behaviour

The ability of a material to recover its original shape after the forces causing deformation have been removed.

Momentum

A physical quantity defined by the relationship $\text{Momentum} = \text{mass} \times \text{velocity}$ ($p = m \times v$), measured in kilogram metres per second ($\text{kg}\,\text{m/s}$).

Force and momentum relationship

The relationship stating that force equals the rate of change of momentum: $\text{Force} = \frac{\text{change in momentum}}{\text{time taken}}$ ($F = \frac{mv - mu}{t}$).

Moment of a force

The turning effect produced by a force, calculated as $\text{moment} = \text{force} \times \text{perpendicular distance from the pivot}$, measured in newton metres ($\text{Nm}$).

Centre of gravity

The specific point through which the entire weight of a body acts.