PHYSICS DEFINITIONS

Vector

Physical quantity that has both magnitude and direction

Scalar

A physical quantity that has magnitude only

Resultant vector

The single vector which has the same effect as the original vectors acting together

Distance

The length of the path travelled

Displacement

A change in position (in space and includes the magnitude and the direction of the straight line from the start to the end of the motion)

Speed

The rate of change of distance

Velocity

The rate of change of position

Acceleration

The rate of change of velocity

Free fall

Motion upwards or downwards in the earth's gravitational field when no other forces act on the object, i.e. only the gravitational force of the earth acts on the body

Equilibrium

The forces acting on an object is in equilibrium when the resultant of all the forces is zero, therefore Fnet = 0

Equilibrant

The equilibrant is the single vector which will bring all the original vectors into equilibrium

Weight

The gravitational force the Earth exerts on any object on or near its surface

Normal force

The perpendicular force exerted by a surface on an object in contact with it

Frictional force

The force that opposes the motion of an object and acts parallel to the surface with which the object is in contact

Newton's first law

An object continues in a state of rest or uniform (moving with constant) velocity unless it is acted upon by a net or resultant force

Inertia

The property of an object that causes it to resist a change in its state of rest or uniform motion

Newton's second law

When a net force, Fnet, is applied to an object of mass, m, it accelerates in the direction of the net force. The acceleration, a, is directly proportional to the net force and inversely proportional to the mass

Newton's third law

When object A exerts a force on object B, object B simultaneously exerts an oppositely directed force of equal magnitude on object A

Triangle law

if 3 forces are in equilibrium, they can be represented in both magnitude and direction by being the three sides if a triangle taken in order