## 1. Mass is defined as the amount of substance in a body

### 1.1. Mass is a scalar quantity

### 1.2. Mass- SI unit: kilogram (kg)

### 1.3. Mass is a constant

## 2. Weight is defined as the gravitational force acting on an object

### 2.1. Weight is not a constant - i.e it varies from location to location (Earth and Moon)

### 2.2. The SI unit for weight is Newton (N)

### 2.3. Weight is a vector quantity

### 2.4. weight is directly proportional to mass since acceleration of a free falling object is a constant.

### 2.5. W=mg, where m is mass and g is gravitational field strength

## 3. Inertia

### 3.1. is defined as the reluctance of an object to change its state of rest or motion due to its mass

### 3.2. the tendency of an object to resist changes varies with mass.

3.2.1. The higher the mass, the higher the inertia- the larger the mass of an object the harder it will be for the object to slow down, move faster or change direction.