Definition

Centre of Mass

It is the point through which the total mass of the object is said to act.

Drag

The resistance against the motion of an object through a fluid. It is usually proportional to the speed of the object.

Efficiency

The useful output (e.g. power, energy) of a system divided by the total output.

Elastic Collision

When the kinetic energy of a system before an event is equal to the kinetic energy of the system after the event.

Equilibrium

An object is at equilibrium when the moments on it about a point are balanced and the resultant force on the object is zero.

Gravitational Potential Energy

The energy gained by an object when it is raised by a height in a gravitational field.

Moment

pivot about which the force is acting.

Momentum

The product of an object’s mass and its velocity.

Newton’s First Law

An object at a constant velocity will remain at a constant velocity unless acted on by a resultant force.

Newton’s Second Law

If an object is acted upon by a resultant force it will accelerate. The acceleration is inversely proportional to the mass of the object and directly proportional to the force acting upon it.

Newton’s Third Law

Every action has an equal and opposite reaction. Equal magnitude but of opposite direction.

Power

The work done by a system divided by the time taken for that work to be done.

Resultant Force

The sum of all forces on an object.

Scalar

A quantity with only magnitude and no direction

Terminal Velocity

The maximum velocity an object can achieve. Acceleration & Resultant force = 0

Vector

A quantity with magnitude and direction .

Weight

The force of gravity on an object, the product of the object’s mass and the acceleration due to gravity.

Work Done

A force applied over a distance, it is the energy transferred in that distance