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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
Known values: Speed \(=\) 50 m/s, and the time \(=\) \(1\) minute (\(60\) seconds).
Substitute the known values in the formula
metres.
Therefore you're covered 3000 metres in a minute., i.e., 50 m/s. But, in which direction?
Remember that speed gives only the magnitude because speed is a 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 to the above question is velocity. Using velocity, we can find the speed with direction.
Now let's understand what velocity is.
Velocity:
Velocity is the rate of change in displacement.
SI unit of velocity is .
Remember, velocity is a 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 only says about speed.
Therefore, velocity is a vector quantity that states the speed as well as the 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 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 bike starting and moving out of railway station.
2. Driving a van in a traffic lane.
In upcoming exercises, We will look into average velocity, and the concepts related to it.
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