# Definition Of Acceleration

## Definition Of Acceleration

"The rate of change of magnitude of velocity".

An object is said to be accelerating if it is changing its velocity.
When an object changes its velocity from ‘u’ to ‘v’ in time ‘t’ seconds.
Then the acceleration of the object = v - u / t = change in velocity / time
= final velocity – initial velocity / time
The S.I. unit of acceleration is m/s2. - Velocity measured in meters/second, and time in seconds.
∴ meter / second X second = ms / s square
Velocity and speed are not same - velocity is a vector quantity i.e., it has both magnitude and direction.
Example - Body moving with a speed of 30 m/s --- Scalar quantity.
Body moving with a speed of 30 m/s towards East -- Vector quantity.

#### Examples of Acceleration:

An elevator moving up
Air craft taking off
Rocket launching

#### Solved Example on Acceleration:

A skater goes from a standstill to a velocity of 6.7 m/s in 12 seconds. What is the acceleration of the skater?

A. 5 m/s2
B. 10 m/s2
C. 5.6 m/s2
D. 0.56 m/s2

#### Solution:

Step 1: Write down the equation needed for solving for acceleration. a = v - u / t
Step 2: Insert the known measurements into the equation.
The initial speed of the skater was zero since he was not in motion. u=0
Step 3:
The skater finally reached a velocity of 6.7 m/s in 12 seconds, v = 6.7: and t = 12
The equation will look like this a = 6.7m / s - 0m / s / 12s
Step 4: Solve. You must solve the change in velocity part of the equation before you divide

Related terms: Uniform acceleration | Deceleration (or) Retardation