Question

A rocket travels at a speed of 15000 m/sec. express in km /hr.

Answer 1

Hint- To solve this question, we need to know the basics of conversion of units. As we know length is one of the physical quantities which has several units of measurement. The S.I. unit is meter while C.G.S. unit is centimeter. Similarly, for time we have various units of measurement like second or hour.

Complete step by step solution:
Given:
A rocket travels at a speed of 15000 m/s and we need to find the speed of the rocket in km/hr.
Now, as we know
‘1 hour = 60 minutes’
‘1 minute = 60 seconds’
1 hour = 60 $ \times $60 = 3600 seconds
Let's see the convention of km/h to m/s:
1 km = 1000 meters.
Hence,
1 seconds = $\dfrac{1}{{3600}}$hr
‘1 kilometer = 1000 meter’
1 meter = $\dfrac{1}{{1000}}$km
Now, as given a rocket travels at a speed of 15000 m/s
To convert m / s to km / hr,
Speed of the rocket = 15000 m/s
                                   = $\dfrac{{{\text{1500 \times 1m}}}}{{{\text{1sec}}}}$
                                   = $\dfrac{{{\text{1500 \times }}\dfrac{{\text{1}}}{{{\text{1000}}}}{\text{km}}}}{{\dfrac{{\text{1}}}{{{\text{3600}}}}{\text{hr}}}}$
                                     = 150 $ \times $36 km/hr
                                    = 54000 km/hr
Therefore, rockets traveling at a speed of 15000 m/sec can be easily expressed in km/hr as shown above.

Note- Generally, the conversion of one unit to another unit of the same quantity is performed using multiplicative conversion factors. Let’s see how to convert a different unit of length. The table for conversion of length is shown below.

The relation between the adjacent unit varies by the multiple of 10 (moving left to right) and vice-versa (i.e. moving right to left).