Question

What are some examples of velocity?

Answer 1

Velocity is defined as the displacement per unit time. Displacement is a quantity that depends on the end points. Displacement is a vector quantity and the magnitude of displacement is the distance between the end points in the motion.

Complete step-by-step answer:
When we talk about motion of any physical body, we feel the need to determine the velocity or speed of the motion that the body is undergoing in order to understand the motion of that body completely. Velocity is a vector quantity and speed is a scalar quantity. When a body has to go from a point A to a point B, then the total distance it covers is a scalar quantity. To understand this better consider that points A and B are placed on diametrically opposite ends in a circle. Now we can cover the circle only by going along the circumference, then in going from point A to point B, the total distance covered is half of the perimeter i.e., $\pi$r. But if we consider the displacement between points A and B then total displacement will be 2r i.e., length of the diameter. This definition helps in understanding better the difference between speed and velocity. If in going from A to B, a time of 1 s has been noted, then the speed will be given as:
$speed = \dfrac{{\pi r}}{{1s}} = \pi r{\text{ m}}{{\text{s}}^{{\text{ - 1}}}}$
And the magnitude of velocity will be given as:
$velocity = \dfrac{{2r}}{{1s}} = 2r{\text{ m}}{{\text{s}}^{{\text{ - 1}}}}$

Note: Circular motion is a very fundamental example in understanding velocity. If anybody is undergoing uniform circular motion then the speed is not changing but the velocity is changing. Because velocity is a vector quantity it changes direction every time as the circle is traversed. Speed is just a scalar. Note here but that magnitude of velocity and speed is the same. The magnitude of velocity is not changing just the direction is changing, so constant acceleration is noted.