Question 81

The earth rotates ${360}^{\circ }$ about its axis in about 24 hours. By how much degree will it rotate in 2 hours?

Given, earth rotates ${360}^{\circ }$ about its axis in about 24 hours i.e.

Rotation by earth in 24 hours = ${360}^{\circ }$

Using unitary method in which first we find the value of one unit and then the value of the required number of units.
$\therefore$ Rotation in 1 hours = $\frac{{360}^{\circ }}{24}$
$\therefore$ Rotation in 2 hours = $\frac{{360}^{\circ }}{24}\times 2$ = ${30}^{\circ }$
Hence, Earth will rotate by ${30}^{\circ }$ in 2 hours.