# Mass, Weight and Density

Get Started. It's Free Mass, Weight and Density ## 1. Mass

### 1.3. SI unit: kilogram (kg)

1.3.1. Other forms of measurements:

1.3.1.1. gram (g)

1.3.1.2. pound (lb)

1.3.1.3. tonne (t)

### 1.4. Constant at any location

1.4.1. Amount of matter in your body is always constant, hence mass doesn't change

### 1.5. Instruments used:

1.5.1. Beam balance

1.5.2. Electronic balance

## 2. Weight

### 2.5. Varies at different locations

2.5.1. depends on the gravity acting on the body

2.5.1.1. eg. the weight of A on Earth (10 m/s^2) would be heavier than the weight of A on moon (1.6 m/s^2)

### 2.6. Instruments used:

2.6.1. spring balance

2.6.2. compression balance

## 3. Inertia

### 3.1. Definition: reluctance of an object to:

3.1.1. start moving (if it was stationary)

3.1.2. stop moving (if it was moving)

### 3.2. Dependent on mass

3.2.1. Greater mass leads to more inertia

### 3.3. Real life examples:

3.3.1. Seat belts: we can still stay in the same position when making a sharp turn/sudden brake as the seat belt increases our inertia

3.3.2. Ships taking a longer time to start and stop moving due to inertia

## 4. Gravitational field strength

### 4.1. Gravitational field: the region in which a mass experiences acceleration due to gravity

4.1.1. Stronger when it's nearer to the centre of the gravitational field and gets weaker as the body is further away

## 5. Inter-relating mass and weight:

### 5.1. Weight = mass x acceleration due to gravity

5.1.1. Newton's 2nd Law of motion: Force = mass x acceleration

5.1.2. Weight is the force

5.1.3. acceleration due to gravity is the acceleration