One yard in $SI$ units is equal to:

The unit of energy in the $SI$ system is:

Universal time is based on:

Select the correct option for one light-year.

$1\,J =$ ............ $\text{calorie}$. (Fill in the blank)

$A$ physical quantity is measured and its value is found to be $nu$, where $n$ is the numerical value and $u$ is the unit. Then which of the following relations is true?