### Theory:

Consider that you're travelling on a bike at a speed of 50 m/s for one minute, can you find the distance that you will cover?

We know the formula to find the distance, that is $\mathit{Distance}\phantom{\rule{0.147em}{0ex}}=\mathit{Speed}\times \mathit{Time}$

**Known values:**Speed \(=\) 50 m/s and the time \(=\) \(1\) minute (\(60\) seconds).

Substitute the known values in the formula

$\mathit{Distance}\phantom{\rule{0.147em}{0ex}}=50\times 60=3000$ meters.

Therefore you're covered 3000 meters in a minute a 50 m/s. But towards which direction?

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

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

So how can we find the speed with direction?

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

Now let's understand what is velocity.

**Velocity:**

Velocity is the rate of change in displacement.

$\mathit{Velocity}(v)\; =\frac{\mathit{Displacement}}{\mathit{Time}}$

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

Remember velocity is the vector quantity which 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 only says about speed.

Therefore, velocity is the vector quantity which states speed as well as direction of an object.

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

**Types of velocity:**

**Uniform velocity**.**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 Earth

**2.**Light travels through vacuum.

**Non uniform velocity:**

If either speed or direction changes, the velocity is non uniform.

Example:

**1.**A bike starting and moving out of the railway station.

**2.**Driving a van in a traffic lane.

**In upcoming exercises we will take a look into average velocity and various concepts deals with it.**