Question

The velocity of a car is 18m/s .Express this velocity in km/h .

Answer 1

To convert a quantity from m/sec to km/hr , just multiply it by 18/5.
18*18/5 = 64.8 km/hr. 

Answer 2

The given velocity of car after the conversion into kilometers per hour is 64.8 km/hr.

Solution:

To convert m/s to km/hr:

1 m $=\frac{1}{1000} km$

1 sec$=\frac{1}{3600} hr$

$1 \mathrm{m} / \mathrm{sec}=\frac{\frac{1}{1000} \mathrm{km}}{\frac{1}{3600} \mathrm{hr}}$

$=\frac{3600}{1000}$

$=\frac{18 \mathrm{km}}{5 \mathrm{hr}}$

So to convert any quantity from m/sec to km/hr it should be multiplied by 18 and divided by 5.  

In the above problem, $18 m/s =18 \times 18$=324 .

$\frac{324}{5}(\mathrm{km}) / \mathrm{hr}=64.8(\mathrm{km}) / \mathrm{hr}$$18 \frac{\mathrm{m}}{\mathrm{s}}=64.8(\mathrm{km}) / \mathrm{hr}$.