## Mass, Weight, Density

by GOH WAN LING SERAPHINA .
## 1. Mass

### 1.1. Definition

1.1.1. Mass is the quantity of inertia possessed by an object or the proportion between force and acceleration referred to in Newton's Second Law of Motion.

### 1.2. Units/ Notation

1.2.1. SI unit: Kilogram (kg)

1.2.2. Other acceptable SI units: Tonnes (t), Electronvolt (eV), Atomic mass unit (u)

1.2.3. Other units: Grams (g), Slug (sl), the Pound (lb), the Planck mass (mP)

### 1.3. Measurements

1.3.1. Weighing scale

1.3.2. The laboratory balance

1.3.2.1. Beam balance and weights

1.3.3. Weighing balance

1.3.4. Automatic check-weighing machines

1.3.5. Katharometer

1.3.6. Inertial balance

1.3.7. Mass spectrometers which measures the mass-to-charge ratio

1.3.8. Aerometer which is used to measure weight of density of gas

1.3.9. Effusion-meter which is used to compare molecular weights of gases

### 1.4. Relation to other quantities

1.4.1. Newton's second law relates the force F exerted in a body of mass m to the body's acceleration a: F=ma (where F is the net force and a is the acceleration of the body)

## 2. Weight

### 2.1. Definition

2.1.1. The weight of an object is defined as the force of gravity on the object. IT IS A FORCE:)

### 2.2. Units/ Notation

2.2.1. SI unit is the Newton(N).

### 2.3. Measurements

2.3.1. Gravity on Earth is about 9.8 N/kg usually taken as 10 N/kg for easy calculations.

2.3.2. It can be calculated by multiplying mass with the gravitational pull of the earth (10 N/kg)

### 2.4. Relation to other quantities

2.4.1. calculated as the mass times the acceleration of gravity, w = mg, where g is the gravitational field strength. This eqn applies at all times even when the object is not accelerating

2.4.2. It can be seen as a different representation of Newton's second Law of Motion: F = ma. Weight will be the resultant force(F) acting on the object that that is in freefall and is subject to nothing but gravity(acc.)

## 3. Inertia

### 3.1. Inertia is the resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion.

### 3.2. What affects inertia?

3.2.1. Mass

3.2.2. Gravity

3.2.3. Friction

3.2.4. Acceleration

### 3.3. Examples of inertia at work

3.3.1. If you throw a tennis ball with the same amount of force as you throw a bowling ball, the tennis ball will go further as it has less mass than the bowling ball.

## 4. Gravitational field strength

### 4.1. Gravity is a force that pulls two objects together. Here on Earth, gravity pulls all things towards the center of the Earth

### 4.2. Relation to other quantities

4.2.1. Mass

4.2.2. Acceleration

4.2.3. Distance

### 4.3. Units/Notation

4.3.1. N/kg

4.3.2. m/s^2

## 5. Density

### 5.1. Definition

5.1.1. The mass density or density of a material is its mass per unit volume.

### 5.2. Units/Notations

5.2.1. SI unit: kilograms per cubic meter (kg/m3)

5.2.2. Other units: kilograms per liter (kg/L), grams per milliliter (g/mL), metric tons per cubic meter (t/m3), grams per cubic centimetre (g/cc, gm/cc or g/cm3)

### 5.3. Measurements

5.3.1. can be measured using displacement of water (for irregular solids) and calculating the volume and measuring the mass (for regular solids).

5.3.2. regular solids include: cuboid, cone, cylinder, sphere, hemisphere

### 5.4. Relation to other quanitities

5.4.1. Density = Mass/Volume