## 1. Inertia

### 1.1. Definition

1.1.1. Inertia is the resistance an object has to a change in its state of motion

1.1.2. The law of inertia states that it is the tendency of an object to resist a change in motion.

### 1.2. Mass and inertia

1.2.1. The mass of a body determines the momentum of the body at given velocity ; it is a proportionality factor in the formula:

1.2.1.1. p=mv

1.2.1.1.1. The factor m is referred to as inertial mass.

1.2.1.2. But mass, as related to the 'inertia' of a body, can also be defined by the formula:

1.2.1.2.1. F=ma

## 2. Gravitational Field Strength

### 2.1. Definition

### 2.2. What is a gravitational field strength?

2.2.1. What is a gravitational field?

2.2.1.1. A gravitational field is a region in which a mass experiences a force due to gravity.

2.2.2. Gravitational field strength g is defined as the gravitational force acting per unit mass.

### 2.3. Units

2.3.1. Newton per Kilogram(N/Kg)

### 2.4. Example

2.4.1. The gravitational field strength on Earth is 10 N/Kg.

## 3. Weight

### 3.1. Defintion

3.1.1. A body's relative mass or the quantity of matter contained by it, giving rise to a downward force; the heaviness of a person or thing.(according to oxford dictionary).

### 3.2. Units

3.2.1. The pound (lb) is the basic unit of weight. Within the English units of measurement there are three different systems of weights. In the avoirdupois system, the most widely used of the three, the pound is divided into 16 ounces (oz) and the ounce into 16 drams. The ton, used to measure large masses, is equal to 2,000 lb (short ton) or 2,240 lb (long ton). In Great Britain the stone, equal to 14 lb, is also used. The troy system (named for Troyes, France, where it is said to have originated) is used only for precious metals. The troy pound is divided into 12 ounces and the troy ounce into 20 pennyweights or 480 grains; the troy pound is thus 5,760 grains. The grain is also a unit in the avoirdupois system, 1 avoirdupois pound being 7,000 grains, so that the troy pound is 5,760/7,000 of an avoirdupois pound. Apothecaries' weights are based on troy weights; in addition to the pound, ounce, and grain, which are equal to the troy units of the same name, other units are the dram (1/8 oz) and the scruple (1/24 oz or 1/3 dram).

3.2.2. The handling of mass and weight depends on the systems of units that is used. The most common systems of units are the • International System - SI • British Gravitational System - BG • English Engineering System – EE

### 3.3. Measurements

3.3.1. Triple Beam Balance

3.3.2. Weighing Scale

3.3.3. Spring Balance

### 3.4. Relation To other quantities

3.4.1. - Weight versus Mass A car's mass is 1,644 kg. The weight can be calculated: w = (1,644 kg)(9.807 m/s2) = 16122.7 N = 16.1 kN - there is a force (weight) of 16.1 kN between the car and the earth. • 1 kg gravitational force = 9.81 N

## 4. Mass

### 4.1. Definition

4.1.1. Mass is the amount of particles in a substance

### 4.2. Units

4.2.1. Milligram(mg)

4.2.2. Gram(g)

4.2.3. Kilogram(kg)

4.2.4. Pound(lb)

4.2.5. Ton(t)

### 4.3. Measurements

4.3.1. Beam balance

4.3.2. Electronic balance

### 4.4. Relation to other quantities

4.4.1. Net force of an object = mass x acceleration

4.4.2. Density of an object = mass/volume