Mass, Weight and Density

1. Mass

1.1. Definition: Amount of matter in a body

1.1.1. Therefore, since it is the number and composition of atoms and molecules that make up the body, no matter the location of the body, the mass will be the same

1.2. SI unit: kilogram (kg)

1.2.1. Other units

1.2.1.1. Grams (g)

1.2.1.2. Tonnes (t)

1.3. Measured by beam balance

1.3.1. Alternatively, common weighing instruments like the electronic balance, spring balance and bathroom scale can be used, but only on Earth as the machines have been calibrated to state mass by dividing our weight by 10.

1.4. Scalar quantity as it does not have a direction

1.5. Mass= Weight/Gravitational Field Strength

2. Weight

2.1. Vector quantity as it has a direction. Its direction is downward, towards the centre of Earth.

2.2. Definition: The weight of an object is the gravitational force, gravity, acting on it

2.3. It is a force. Thus, like all other forces, the SI unit of weight is Newton(N).

2.4. Weight=Mass(times)Gravitational Field Strength

3. Gravitational Field

3.1. Definition: A region in which mass experiences a force due to gravitational attraction

3.2. Gravity is strongest at the surface of the Earth and gets weaker further away.

4. Gravitational Field Strength

4.1. Definition: Gravitational Field Strength g is defined as the gravity acting per unit mass

4.2. The heavier the mass of the object, the greater the weight

4.3. On earth approximately 10 N/kg

4.4. On moon 1.6 N/kg

4.5. Gravitational Field Strength=Weight/Mass

5. Inertia

5.1. Definition: The inertia of an object refers to the reluctance of the object to change its state of rest or motion, due to its mass

5.2. Greater mass,greater inertia

5.3. Thus,need seatbelt to stop one from motion

6. Density

6.1. Definition: The density of a substance is its mass per unit volume

6.2. SI unit: kg/m(cube)