Question

A boy cycles a distance of \[640\text{ m}\] in $2$ minutes and $40$ seconds. What is the speed of the cycle?

Answer 1

Hint : To solve these types of questions we must know the formula that we can use to calculate the speed with the help of distance covered in a given time by the body. We know that speed is distance covered by a body in per unit time, hence we will use this information to solve this problem and calculate the speed of the cycle.

Complete step-by-step solution:
We know that the speed of the cycle can be found out by dividing the distance covered by the cycle with the time taken by the cycle to cover the distance. But before proceeding we must notice that the time taken by the cycle to cover \[640\text{ m}\] must be converted to SI units. Hence the time taken by the cycle in seconds would be as follows:
$\begin{align}
  & t=2\times 60+40 \\
 & \Rightarrow t=120+40 \\
 & \Rightarrow t=160\text{ s} \\
\end{align}$
After finding out the time taken by the cycle to cover \[640\text{ m}\] in SI units, we can now proceed to find the speed of the cycle by substituting the values of distance covered by the cycle in the given time which will be as follows:
$\begin{align}
  & v=\dfrac{\text{Distance}}{\text{Time}} \\
 & \Rightarrow v=\dfrac{640}{160} \\
 & \therefore v=4\text{ m}{{\text{s}}^{-1}} \\
\end{align}$
Thus, the speed of the cycle if it covers a distance of \[640\text{ m}\] in $2$ minutes and $40$ seconds will be $4\text{ m}{{\text{s}}^{-1}}$.

Note: To solve these types of questions we must always make sure that we use the quantities in their correct units otherwise we could get an error in our answers. In the question we had to find out the speed of the cycle, if we were to find its velocity then we would have also mentioned the direction of the cycle.