Physical World Word List

Acceleration

A change in velocity over a period of time that is caused by an unbalanced force. Has the units of metres per second squared (m/s² or m s-2) and the acceleration will be in the direction of the net force.

Rectangular Component

The parts of a vector resolved into vertical and horizontal vector components. Rectangular components are perpendicular to each other.

Displacement

A vector quantity that measures the change between two positions of an object along the shortest path connecting them.

Distance

A scalar quantity that measures the change of position of an object between two locations along the actual path connecting them.

Equilibrium

A state of balance resulting from the application of two or more forces that produce a zero net force.

Field

A region in which a body experiences a force due to the effects of another body. The effect can be the mass within the bodies, their charges or magnetic properties.

Force

An influence that acts to change the motion of a body or to impose an elastic strain on it.

Free body diagram

A diagram showing the vectors acting on a body, usually drawn with the vectors originating at the centre of mass of the object.

Friction

A force that always opposes motion.

Gradient

Measures the rate of change of the vertical quantity to a horizontal quantity on a line graph. Calculated using rise/run. Usually gradients in run Physics have associated units.

Gravitational force

The force of attraction between all masses in the universe; especially the attraction of the earth's mass for bodies near its surface

Inertia

The tendency of an object to resist changes in its state of motion

Mass

How much matter an object has; measured in kilograms

Newton

The unit of force (symbol N).

Resultant vector

Is the sum of two or more vectors of the same type.

Scalar

A quantity that can be fully described by magnitude and units.

Speed

Is a scalar quantity that is the rate at which an object covers distance. Calculated by the distance travelled divided by the time interval. Has units of metres per second (m/s or m s-1)

Vector

A quantity that needs magnitude, units and direction to fully describe it (MUD).

Velocity

Is a vector quantity that is the change in displacement over a period of time. Calculated by the displacement travelled divided by the time interval. Has units of metres per second (m/s or m s¹)

Weight

The force of attraction of an object to a large central mass, usually a planet. Measured in newtons.