a physical quantity is a quantity that can be measured. it consists of a numerical magnitude and a unit

scalar quantities are physical quantities that have only magnitude

vector quantities are physical quantities that have both magnitude and direction

one oscillation is each complete to-and-fro motion

the period of a simple pendulum is the time taken for one complete oscillation

speed is the distance moved per unit time

velocity is the rate of change of displacement

instantaneous speed is the speed of an object at a particular instant

uniform speed is when the change in the distance travelled by an object per unit time is the same

acceleration is the rate of change of velocity

uniform acceleration is a constant rate of change of velocity

mass is the measure of the amount of matter in a body

a gravitational field is a region in which a mass experiences a force due to gravitational attraction

gravitational field strength g is defined as the gravitational force per unit mass placed at that point

weight is the gravitational force acting on an object

a force is a push or pull due to an interaction between objects to explain changes in motion

distance is the total length covered by a moving object regardless of direction of motion

displacement is the distance measured in a straight line from a fixed reference point

newtons first law of motion states that every object will continue in its state of rest or uniform motion in a straight line unless a resultant force acts on it

the inertia of an object refers to the reluctance of the object to change its state of rest or motion, due to its mass

newtons second law of motion states that when a resultant force acts on an object of a constant mass, the object will accelerate in the direction of the resultant force

newton's third law of motion states that if body A exerts a force Fab on body B, body B will exert an equal and opposite force Fba on body A

friction is the contact force that opposes or tends to oppose motion between surfaces in contact

the principle of moments states that when a body is in equilibrium, the sum of clockwise moments about a pivot is equal to the sum of anticlockwise moments about the same pivot

the centre of gravity of an object is an imaginary point where the entire weight of the object seems to act

the stability of an object is a measure of its ability to return to its original position

pressure is the force acting per unit area

if a pressure is applied to an enclosed liquid, the pressure is transmitted to all other parts of the liquid undiminished

density is defined as mass per unit volume

the principle of conservation of energy states that energy cannot be created or destroyed. energy can be transferred from one store to another. the total energy of an isolated system is constant

work done by a constant force on an object is the product of the force and the distance moved by the object in the direction of the force

power is defined as the work done or energy transferred per unit time

the kinetic particle model of matter is made up of tiny particles that are in continuous motion

thermal equilibrium describes a state in which two or more objects have the same temperature and there is no net transfer of energy between them