Question

A car moves with a speed of 80 km/hr. What is the speed of the car in meters per second?
$
  {\text{A}}{\text{. }}22\dfrac{2}{9}m/s \\
  {\text{B}}{\text{. }}8m/s \\
  {\text{C}}{\text{. }}20\dfrac{1}{9}m/s \\
  {\text{D}}{\text{. }}8\dfrac{2}{3}m/s \\
 $

Answer 1

Hint: Here we go through by converting the kilometer into meter and hour to second to convert the speed from km/hr. to m/s.

Complete step-by-step answer:
Here in the question it is given that a car moves with a speed of 80 km/hr.
Now as we know that 1 kilometer is equal to 1000meter.
And now we have to convert hour into sec,
As we know 1 hour= 60 min and 1 min=60 sec.
Therefore we can say that 1 hour=$60 \times 60 = 3600s$
We will write 80km/hr. as$\dfrac{{80km}}{{1hour}}$.
Now for converting into m/s we have to convert 80 km into meters and 1 hour into second.
So we will write it as,
$ \Rightarrow \dfrac{{80km}}{{1hour}} = \dfrac{{80 \times 1000m}}{{1 \times 3600s}} = \dfrac{{80}}{1} \times \dfrac{5}{{18}} = \dfrac{{200}}{9} = 22\dfrac{2}{9}m/s$
Hence option A is the correct answer.

Note: Whenever we face such a type of question the key concept for solving the question is to convert the data one by one in which the question asked the result. And for this question we will apply a short trick after solving we will get that short trick that we have to simply multiply by $\dfrac{5}{{18}}$ to convert km/hr. to m/s. and vice versa we will multiply by $\dfrac{{18}}{5}$ to convert from m/s to km/hr.