Kinematics and Forces

Scalar

A physical quantity that has magnitude only.

Vector

A physical quantity that has magnitude and direction

Examples of scalars

Speed, distance, time, temperature, energy, mass, volume

Examples of vectors

Velocity, displacement, acceleration, force, weight

examples of contact forces

friction, normal force, tension

examples of non contact forces

magnetic, gravitational, electrostatic

Resultant vector

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

Resultant force

The single force which has the same effect as the original forces acting together

Position

A vector quantity that points from the reference point as the origin

Distance

The length of the path travelled

Displacement

A change in position

Resultant displacement

The single displacement that represents the combined effect of two or more displacements

Speed

rate of change of distance

Velocity

The rate of displacement

Converting km/h to m/s

divide by 3.6

Converting ms-1 to kmhr-1

multiply by 3.6

Average velocity

The rate of displacement measured over the entire journey

instantaneous velocity

The rate of displacement at a specific point in time

Acceleration

rate of change of velocity

Weight

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

Gravitational acceleration

9.8 m/s^2

Free fall

An object moving up or down under the influence of only gravitational force

force

A push or a pull

mass

the quantity of matter in an object

normal force

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

friction

a force that opposes the motion of an object

tension

force transmitted through a rope or wire when it's stretched

equilibrium

when all the forces on an object ballance (FNet=0)

equilibrant

a balancing force

Newton's first law

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

Newton's second law

when a net force is applied to an object of mass, it accelerates in the direction of the net force. This acceleration 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

Newton's law of universal gravitation

Every particle with mass in the universe attracts every other particle with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers

Gravitational field description

a region of space surrounding an object that can exert a force on other objects that are placed within that region

Gravitational field definition

the force acting per unit mass