Question

Speed of $90km/h$ when expressed in $m/s$ is _____.

• A. $9000m/s$
• B. $90m/s$
• C. $25m/s$
• D. $20m/s$

Answer 1

The correct option is C

$25m/s$

Step 1: Given data
Speed $=90km/h$

Step 2: Converting the speed from $km/h$ into $m/s$

We know that $1km=1000m$ and $1h=60\times 60s=3600s$.

To convert $km/h$ into $m/s$, simply put the values of kilometers in meters and the value of hours in seconds.

$$\begin{gathered} 90km/h=90\times \frac{1000m}{3600s} \\ \Rightarrow 90km/h=90\times \frac{5}{18}m/s \\ \Rightarrow 90km/h=25m/s \end{gathered}$$

So, the speed of $90km/h$ when expressed in $m/s$ is $25m/s$.

Hence, the correct answer is option C.