# Physics

### Chapter : 1. Motion

#### Types of Acceleration

Acceleration
Rate of change of velocity is called acceleration. It is a vector quantity
i.e. Unit of acceleration = m/s2 or ms–2
Types of acceleration
Uniform & Non Uniform Acceleration
Uniform Acceleration
If a body travels in a straight line and its velocity increases by equal amounts in equal intervals of time then it is said to be in state of uniform acceleration.
e.g. motion of a freely falling body.
Non uniform acceleration
A body has a non-uniform acceleration if its velocity increases by unequal amounts in equal intervals of time.
Instantaneous Acceleration
The acceleration of a body at any instant is called its instantaneous acceleration.
If the velocity of a body decreases, then it will experience a negative acceleration which is called deceleration or retardation.
Acceleration is determined by the slope of time-velocity graph.
tan θ = (i) If the time velocity graph is a straight line, acceleration remains constants.
(ii) If the slope of the straight line is positive, positive acceleration occurs.
(iii) If the slope of the straight line is negative, negative acceleration or retardation occurs.