Parameters of Motion-
We have discussed, the motion of a body may be described through the following parameters-
Before you go through this article, make sure that you have gone through the previous article on Speed and Velocity.
In this article, we will discuss about acceleration.
|It is defined as the rate of change of velocity of a body with time.|
Characteristics of Acceleration-
- The SI unit of acceleration is meter per square second (m/s2).
- The dimensional formula of acceleration is [LT-2].
- It has both magnitude and direction. Hence, it is a vector quantity.
- The direction of acceleration is same as direction of change in velocity.
- It may be positive, negative or zero.
Also Read- Distance & Displacement
Example On Acceleration-
Consider a car starting from rest acquires a speed of 50 m/s in 5 seconds. Then, its acceleration is given by-
= Change in velocity / Time taken
= (Final velocity – Initial velocity) / Time taken
= (50 – 0) / 5
= 10 m/s2
Different Types of Acceleration-
There are following 4 different types of acceleration-
1. Uniform Acceleration
2. Variable Acceleration
3. Average Acceleration
4. Instantaneous Acceleration
1. Uniform Acceleration-
|The acceleration of a body is said to be uniform acceleration if its velocity changes by equal amounts in equal intervals of time.|
2. Variable Acceleration-
|The acceleration of a body is said to be variable acceleration if its velocity changes by unequal amounts in equal intervals of time.|
3. Average Acceleration-
|For a body moving with variable velocity,
the average acceleration is defined as the ratio of the total change in velocity of the body to the total time interval taken.
- At time t1, initial velocity of the body = u
- At time t2, final velocity of the body = v
Then, its average acceleration is-
4. Instantaneous Acceleration-
|The acceleration of the body at a given instant of time is called its instantaneous acceleration.|
It is equal to the limiting value of the average acceleration of the body in small time interval around that instant, when the time interval approaches zero.
The instantaneous acceleration of a body is equal to the first order derivative of velocity and second order derivative of position with respect to time.
Relation Between Direction of Velocity & Acceleration-
It is important to remember the following two points-
- If velocity and acceleration are in the same direction, then velocity of the body increases.
- If velocity and acceleration are in the opposite directions, then velocity of the body decreases.
When acceleration acts in the opposite direction of velocity, it is called as retardation.
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