## Physics

by nrliman -
## 1. Chapter 3 : Forces & Pressure

### 1.1. Free-body diagrams

1.1.1. addition of parallel vectors

1.1.2. addition of non- parallel vectors

1.1.2.1. 1. Choose scale 2. Draw arrows to represent forces 3. Complete parallelogram 4. R.F is represented by the diagonal of the parallelogram. - magnitude = diagonal - direction= angle from horizontal line.

### 1.2. Pressure

1.2.1. SI Unit : Pa p = f/a

### 1.3. Motion of objects

1.3.1. Newton's 1st law of motion Every object will continue in its state of rest or uniform motion in a straight line unless a R.F acts on it.

1.3.1.1. Balanced forces

1.3.1.1.1. R.F = 0 Acceleration = 0 Object at rest will remain at rest. Object in motion will remain at constant velocity.

1.3.2. Newton's 2nd law of motion When a R.F acts on an object of constant mess, the object will accelerate in the direction of the R.F. R.F = ma

1.3.2.1. Unbalanced forces

1.3.2.1.1. R.F ≠ 0 Acceleration ≠ 0 Object at rest will move Object in motion will change its velocity

1.3.3. Newton's 3rd law of motion If body A exerts a force on body B, then body B will exert an equal & opposite force on body A.

### 1.4. Effects of force

1.4.1. A body at rest moves

1.4.2. A moving body increases in speed

1.4.3. A moving body decreases in speed

1.4.4. A moving body changes direction

## 2. Chapter 1 : Measurement

### 2.1. Physical quatity

2.1.1. can be measured and consist of a unit and magnitude.

### 2.2. Vector quatity

2.2.1. can be measured and consist of a unit, magnitude and direction.

### 2.3. Prefixes

2.3.1. cannot measure thin objects.

2.3.2. kilo - k mega - M giga -- tera - milli - m micro - nano - pico -- deci - d - 10^-1 centi - c - 10^-2

### 2.4. Vernier calipers

2.4.1. 0.01cm / 0.1mm

2.4.1.1. check for zero error!

2.4.1.2. check if the zero mark coincides with the zero mark on the vernier scale when the outside jaws touch each other.

### 2.5. Micrometer screw gauge

2.5.1. 0.01mm / 0.1cm

2.5.1.1. check for zero error!

2.5.1.2. check if the smallest reading is 0.00mm, where the spindle touches the anvil. +Below datum line - positive +Above datum line - negative

2.5.2. measure thick to thin objects.

## 3. Chapter 4 : Mass, Weight, Density

### 3.1. Mass

3.1.1. Amt. of substance in a body

3.1.2. Is a measure of inertia

### 3.2. Weight

3.2.1. The gravitational force acting on an object

3.2.2. SI Unit : N W = mg

3.2.3. Gravitational field strength is the gravitational force acting per unit mass.

3.2.3.1. Gravitational field is a region in which a mass experiences a force due to gravitational attraction.

### 3.3. Inertia

3.3.1. The reluctance of the object to change its state of rest or motion due to its mass.

### 3.4. Density

3.4.1. Mass per unit volume

3.4.2. SI Unit : kg/m^3 p = m/v

## 4. Chapter 2 : Kinematics

### 4.1. Scalars

4.1.1. Physical quantities with units and magnitude only.

4.1.2. Speed

4.1.2.1. Scalar quantity SI Unit : m/s

### 4.2. Vectors

4.2.1. Distance

4.2.1.1. SI Unit : m

4.2.2. Physical quantities with units, magnitude and direction.

4.2.3. Velocity

4.2.3.1. SI Unit : m/s Velocity = displacement/time

4.2.4. Acceleration

4.2.4.1. a = V-U / T

4.2.5. Displacement

### 4.3. Graphs

4.3.1. The gradient in distance - time graph gives the speed.

4.3.2. The gradient in Speed - time graph gives the acceleration.

4.3.3. The area under speed - time graph gives the distance.