When the body moves with a constant speed in a fixed direction we say that the body is moving with constant velocity. An automobile traveling on a straight, flat highway at a constant speed is a good example for constant velocity. In this section we will learn more about constant velocity.

When a body travels in a straight line and covers equal distance in equal intervals of time, it is said to have constant velocity. Thus, a body is said to have constant velocity if it covers equal distance in equal intervals of time, and in a straight line.
For example, a car travelling with a constant speed in a straight line has constant velocity.
When the instantaneous velocity of a body does not change, it is moving at a constant velocity. For the case of constant velocity, the basic formula $v = \frac{s}{t}$ can be rewritten to give the distance covered in a given period of time:
$Distance$ = $Constant\ velocity \times time$
$s = v \times t$
$s = v \times t$
Another way to write $v$ = $\frac{s}{t}$ gives the time need to cover a given distance at the constant velocity $v$:
$Time$ = $\frac{Distance}{Constant\ Velocity}$
$t$ = $\frac{s}{v}$
The velocitytime graph for constant velocity is shown below. Which is a horizontal line parallel to the x axis. The slope of the graph is zero. That is the acceleration of an abject moving with constant velocity is zero.
The following are the problems of constant velocity.
Solved Examples
Question 1: A car moving with a constant velocity of 160 kmh^{1}. How do you calculate the distance travelled by the car in 36 s?
Solution:
Solution:
Given,
Velocity = $160$ kmh^{1} = $160 \times$ $\frac{5}{18}$ ms^{1} = $\frac{400}{9}$ ms^{1}
Time taken = $36$ s
The formula for velocity = $\frac{Distance\ travelled}{Time\ taken}$
$Distance$ = $Velocity \times Time$
= $\frac{400}{9}$ ms^{1} $\times 36$ s
= $1600$ m
= $1.6$ km
= $1.6$ km
Question 2: In a 1000 metre race, the winner takes 20 seconds to reach the finishing point. Calculate the the velocity of the winner.
Solution:
Solution:
Given,
Displacement = $1000$ m
Time= $20$ s
Then the velocity of the winner = $\frac{Total\ distance\ travelled\ along\ a\ straight\ line}{Total\ time\ taken}$
= $\frac{1000}{20}$
= $50$ m/s
The velocity of the winner is $50$ m/s.
Question 3: How do you calculate the constant velocity of bus which has the displacement 200 metre with 10 seconds?
Solution:
Solution:
Given,
Displacement of bus = $200$ m
Time taken = $10$s
Then the velocity = $\frac{Displacement}{Time}$
= $\frac{200}{10}$
= $20$ m/s
The velocity of bus is $20$ m/s.