Question
Express $15 m s ^{-1}$ in $km h ^{-1}$.
✓
Answer
1 metre $=\frac{1}{1000} \mathrm{~km}$
15 metre $=\frac{15}{1000} \mathrm{~km}$
1 second $=\frac{1}{3600} \mathrm{hr}$
Here, Distance $=\frac{15}{1000} \mathrm{~km}$
Time taken $=\frac{1}{3600} \mathrm{hr}$.
Speed $=\frac{\text { Distance }}{\text { Time taken }}$
$ =\frac{\frac{15}{1000}}{\frac{1}{3600}}$
$ =\frac{15}{1000} \times \frac{3600}{1}$
$=54 \mathrm{~km} \mathrm{~h}^{-1}$
15 metre $=\frac{15}{1000} \mathrm{~km}$
1 second $=\frac{1}{3600} \mathrm{hr}$
Here, Distance $=\frac{15}{1000} \mathrm{~km}$
Time taken $=\frac{1}{3600} \mathrm{hr}$.
Speed $=\frac{\text { Distance }}{\text { Time taken }}$
$ =\frac{\frac{15}{1000}}{\frac{1}{3600}}$
$ =\frac{15}{1000} \times \frac{3600}{1}$
$=54 \mathrm{~km} \mathrm{~h}^{-1}$
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