1. Mass
1.1. Mass is the amount of matter in a body.
1.2. SI Unit: kilogram (kg)
1.3. It is a property of a body that does not change with its location/ shape. It is dependent on the number and composition of atoms and molecules that make up the body.
1.4. Mass and Weight: weight=mass x gravity
1.5. Mass and Inertia: Mass and Weight: The tendency of an object to resist changes in its state of motion varies with mass. Mass is that quantity that is solely dependent upon the inertia of an object. The more inertia that an object has, the more mass that it has. A more massive object has a greater tendency to resist changes in its state of motion.
1.6. Mass and Gravitational Field Strength: gravity=weight/mass
2. Weight
2.1. The weight of an object is the gravitational force or gravity acting on it.
2.2. Weight is a force
2.2.1. SI unit : newton (N)
2.2.2. Vector quantity
2.3. Weight = Mass X Gravitational acceleration (w=mg)
2.4. Direction of weight is downwards (towards the centre of the earth)
2.5. Weight and Gravitational Field Strength
2.5.1. The weight of an object depends on the strength of the gravitational force acting on it.
2.5.2. The gravitational force is the strongest at the surface of the Earth and gets weaker further away.
2.5.3. Example --> Object weighs less on the moon than on Earth because the gravitational field strength on the Moon is weaker as compared to the strength on Earth.
3. Inertia
3.1. Inertia is the reluctance of an object to change its state of rest or motion in a straight line.
3.1.1. As Newton's First Law states, "An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force."
3.2. The greater the mass, the greater the inertia.
3.2.1. The tendency of an object to resist changes in its state of motion varies with mass. Mass is that quantity that is solely dependent upon the inertia of an object. The more inertia that an object has, the more mass that it has. A more massive object has a greater tendency to resist changes in its state of motion.
3.3. S.I Unit - kg/m^2
3.4. Examples of inertia
3.4.1. Safety belt on a car opposes the force when a car in motion comes to an abrupt halt.
3.4.2. A ball rolling will continue to roll unless a friction or another force acts on it.
3.4.3. If pulled quickly, a tablecloth can be removed from underneath of dishes.
3.5. Inertia is directly proportional to mass.
3.5.1. K.E = 1/2mv^2
3.5.1.1. When K.E increases, P.E =mgh
4. Gravitational Field Strength
4.1. Gravitational field strength g is defined as the gravitational force acting per unit mass
4.2. SI unit: g
4.3. g = weight/mass
4.4. Gravitational field strength vs gravitational field
4.4.1. the gravitational force acting per unit mass
4.4.2. gravitational field is a region in which a mass experiences a force due to gravitational attraction