Question

A speed of 14 meters per second is the same as:
A.28 km/hr
B.46.6 km/hr
C.50.4 km/hr
D.70 km/hr

Answer 1

Hint: From the above question and based on options, it is clear that we need to convert meters to kilometers and seconds to hours. So we need to know the conversions of length and conversions of time. So, we need to convert 14 meters per second into kilometers per second.

Complete step-by-step answer:
Given, 14 meters / second
Definition of speed: Measured as distance traveled per unit of time.
Definition of Kilometer: A kilometer (km) is a decimal multiple of the meter, the international standard unit of length, approximately equivalent to 39370.07 inches. A kilometer is now used officially for expressing distances between two places or points.
Definition of meters: A meter (m) is the base unit of length in the International System of Units (SI).
Therefore, 1km = 1000 meters
$\Rightarrow$1 meter = ${\displaystyle \frac{1\text{ km}}{1000}}$
Definition of Hour: A period of time equal to 60 minutes that is 3600 seconds.
Definition of second: It is measured as the smallest unit of time.
$\Rightarrow$1 second =${\displaystyle \frac{1\text{ hr}}{3600}}$
Now, $14$meters per second need to be converted to kilometers per hour.
Let x be 14 meters per second which is needed to convert into kilometers per hour
$\Rightarrow$$\text{x = 14}{\displaystyle \frac{\text{m}}{\text{s}}}$
$\Rightarrow 14{\displaystyle \frac{{\displaystyle \frac{1\text{ km}}{1000}}}{{\displaystyle \frac{1\text{ hr}}{3600}}}}$
$\Rightarrow {\displaystyle \frac{14\times 3600}{1000}}{\displaystyle \frac{\text{km}}{\text{hr}}}$$=50.4{\displaystyle \frac{\text{km}}{\text{hr}}}$
Therefore, 14 meters per second is equal to 50.4 kilometers per hour

Note: For this problem, there is a standard equation for this type of conversion. To convert a Kilometer per hour into meter per second, we need to multiply by 5 and then divide it by 18. This standard form got from this ${\displaystyle \frac{{\displaystyle \frac{1\text{ km}}{1000}}}{{\displaystyle \frac{1\text{ hr}}{3600}}}}$fraction which we used in the solution to solve. When we solve this fraction we will get the above form.