Question

If the acceleration due to gravity is $10m{s}^{-2}$ and the units of length and time are changed in kilometer and hour respectively, the numerical value of the acceleration is

• A.
  $72,000$
• B. $129600$
• C. $360000$
• D. $36000$

Answer 1

The correct option is B $129600$

As we know, the acceleration is given as,
$1m{s}^{-2}=\frac{1m}{1s\times 1s}$
$1m={10}^{-3}km$ and $1hr=3600s$
Therefore,
$1m{s}^{-2}=\frac{1\times {10}^{-3}km}{\frac{1}{3600}hr\times \frac{1}{3600}hr}$
$1m{s}^{-2}=12960kmh{r}^{-2}$
The acceleration due to gravity is given as, $10m{s}^{-2}=129600kmh{r}^{-2}$
Thus, the numerical value of acceleration is $129600$.