 PUMPA - THE SMART LEARNING APP

Take a 10 minutes test to understand your learning levels and get personalised training plan!

Consider that you're travelling on a bike at a speed of 50 $$\frac{m}{s}$$ for $$1\ minute$$.

Can you find the distance without actually using any measuring distance?

Yes, we know the formula to find the distance, that is

$\mathit{Distance}\phantom{\rule{0.147em}{0ex}}=\mathit{Speed}×\mathit{Time}$

Known values:

Speed $$=$$ 50 $$\frac{m}{s}$$

Time $$=$$ $$1$$ $$minute$$ $$=$$ $$60$$ $$seconds$$

Substitute the known values in the formula,

$\mathit{Distance}\phantom{\rule{0.147em}{0ex}}=50×60=3000$ $$m$$

Therefore, you have covered 3000 $$m$$ in a minute at 50 $$\frac{m}{s}$$. But, in which direction?

Remember that speed gives only the magnitude because speed is the scalar quantity. It does not give direction.

Therefore, speed only tells us how much distance covered in unit time but not the direction.

So, how can we find the speed with direction?

The answer to the above question is velocity. Using velocity, we can find the speed with direction.

Now let us understand about velocity.

Velocity
Velocity is the rate of change in displacement.

The SI unit of velocity is $\frac{\mathit{metre}\phantom{\rule{0.147em}{0ex}}\left(m\right)}{\mathit{second}\phantom{\rule{0.147em}{0ex}}\left(s\right)}=\frac{m}{s}=m{s}^{-1}$.

Remember, velocity is the vector quantity that tells the direction of an object.

Therefore, when you mention velocity, you must keep track of direction.
Example:
The bike travels south at 50 km per hour - This statement states velocity.

The bike travels at 50 km per hour - This statement says about speed.

Therefore, velocity is the vector quantity that gives the speed and direction of an object.

Velocity can be of two types with respect to displacement and time.

Types of velocity
1. Uniform velocity
2.  Non-uniform velocity
Uniform velocity
An object has uniform velocity if it covers equal displacement in the same direction in equal intervals of time.
Example:
1. Rotational speed of the Earth
2. Light travels through a vacuum
Non-uniform velocity
If either speed or direction changes, the velocity is non-uniform.
Example:
1. A train starting and moving out of the railway station
2. Driving a bike in a traffic lane
In upcoming exercises, we will look into average velocity, and various concepts related with it.