Acceleration

Imagine you are driving along a highway ...

You are moving at a constant speed of 15 m/s along the straight road. Can you tell - what kind of motion your are in?

Yes! By your knowledge in kinematics, you can confidently answer that you are in "Uniform Motion".

And you are traveling with a constant speed, so you are covering equal distances in equal intervals of time and your direction is also not changing.

Thus, your velocity remains constant and your answer is absolutely right!

After a while, you press the accelerator of the car and your car starts increasing its speed...

Now your speed constantly increases from 15 m/s to 20 m/s to 25 m/s to 30 m/s and so on.

You are now covering more and more distance in same intervals of time, and your velocity is not uniform anymore.

So, now your motion is " $N o n - U n i f o r m M o t i o n$ ".

Also if you record your velocity change with time, you can notice that your velocity keeps on increasing by 5 m/s for every minute.

Now, how can you now express this gradual change in the velocity and talk about your motion in more detail?

We can express the change in velocity of a body using a physical quantity called $" A c c e l e r a t i o n "$ .

Acceleration is defined as the "rate of change of velocity".

So mathematically, acceleration, is the measure of change of velocity of an object within a given time-interval.

If velocity of an object changes from $u$ to $v$ in a time interval $t$ , then acceleration $a$ is calculated using the above formula.

As shown above, your car's acceleration in the 1st minute can be calculated from this relation.

Similarly, the accelerations for every minute can also be calculated using the formula.

We can see, that the value of acceleration is uniform throughout the journey.

This kind of motion, where our velocity gradually changes uniformly is known as $u n i f o r m l y a c c e l e r a t e d m o t i o n$ .

Let us know more about "Acceleration"

Just like velocity, acceleration is also a vector quantity, which means acceleration also has both magnitude as well as direction.

If velocity continuously increases with time, then acceleration is always positive.

And if velocity continuously decreases with time then acceleration is negative which is also called $d e c e l e r a t i o n$ or $r e t a r d a t i o n$ .

Since, SI unit of velocity is $m / s$ and acceleration is the rate of change of velocity, then the unit of Acceleration will be (unit of velocity)/(unit of time) i.e., $\frac{m}{s ^{2}}$

Now it's time for 'Revision'

$A c c e l e r a t i o n$ is the rate of change of velocity.

$∙$ SI unit of Acceleration is $m / s^{2}$ . $∙$ CGS unit of Acceleration if $c m / s^{2}$ .

If the velocity of the car changed from $u$ to $v$ in time $t$ , the acceleration $a$ is calculated using the above relation

The end.