Introduction
Motion refers to the change in position of an object with respect to time. An object is said to be in motion when its position changes compared to a fixed reference point.
Types of Motion
- Rectilinear Motion – Motion along a straight line.
Example: A car moving on a straight road. - Circular Motion – Motion along a circular path.
Example: Hands of a clock. - Periodic Motion – Motion that repeats at regular intervals.
Example: Pendulum motion. - Uniform Motion – Object covers equal distances in equal intervals of time.
- Non-uniform Motion – Object covers unequal distances in equal intervals of time.
Distance and Displacement
| Distance | Displacement |
|---|---|
| Total path covered | Shortest distance between two points |
| Scalar quantity | Vector quantity |
| Always positive | Can be zero or negative |
Speed
- Distance travelled per unit time.
- Formula:
Speed = Distance ÷ Time - Unit: m/s
Types of Speed
- Uniform speed
- Non-uniform speed
- Average speed
Velocity
- Displacement per unit time.
- Formula:
Velocity = Displacement ÷ Time - Unit: m/s
Acceleration
- Rate of change of velocity.
- Formula:
Acceleration = Change in velocity ÷ Time - Unit: m/s²
Equations of Motion
- v = u + at
- s = ut + ½at²
- v² = u² + 2as
Where:
u = initial velocity
v = final velocity
a = acceleration
t = time
s = distance
Graphical Representation of Motion
- Distance–Time Graph
- Straight line → Uniform motion
- Curve → Non-uniform motion
- Velocity–Time Graph
- Area under graph → Distance travelled
- Slope → Acceleration
Uniform Circular Motion
- Speed is constant but velocity changes due to continuous change in direction.
- Acceleration acts towards the center.
Quick Short Q&A (Most Possible)
| Question | Short Answer |
|---|---|
| What is motion? | Change in position with time |
| Unit of speed? | m/s |
| Unit of acceleration? | m/s² |
| Uniform motion? | Equal distance in equal time |
| Non-uniform motion? | Unequal distance in equal time |
| Speed vs velocity? | Velocity has direction |
| Distance–time graph of uniform motion? | Straight line |
| Area under velocity–time graph gives? | Distance |
| Formula for acceleration? | (v − u)/t |
| Equations of motion count? | Three |