Question

In a $100m$ race the winner takes $10s$ to reach the finishing point. The average speed of the winner is
(A) $5$
(B) $10$
(C) $20$
(D) $40$

Answer 1

Hint: To solve this problem we need to know the formula for average speed. The average speed of a body at a certain time interval is defined as the distance covered by the body in that time interval divided by time. It is a scalar quantity.
Distance is a scalar quantity which indicates how much ground has been covered by the object.

Complete Step by Step Solution:
Distance covered by the winner, ‘S’ $ = 100m$
Time taken by the winner to reach the finishing point, ‘t’ $ = 10s$
Average speed of the winner, $v = \dfrac{s}{t}$
$ \Rightarrow v = \dfrac{{100}}{{10}}$
$ \Rightarrow v = 10m{s^{ - 1}}$

Hence the correct option is B

Additional information:
Displacement is a vector quantity, and it is the shortest possible distance between the start and end point.
The average velocity of a body in a certain time interval is defined as the displacement of the body in that time interval divided by time.
Initial velocity describes how fast an object can travel when gravity applies force on the object and final velocity is the velocity which measures the speed and direction of the moving body once it has reached the maximum acceleration.
The main difference between speed and velocity is that speed gives us idea about only about fast is an object moving whereas velocity gives idea about magnitude and direction of the moving body

Note:
Tangential velocity: It can be defined as when an object is moving around a circular path the body’s velocity is tangential at any instant.
Angular velocity: It can be defined as the rate of change of angular displacement with time.
Angular displacement: It is the degree or angle through which an object has been rotated in the specified axis.