Question

Different minerals are being mined from within the earth and multi-storeyed are being constructed. Due to this activity theoretically

• A. Angular speed of earth would increase
• B. Angular momentum would increase
• C. Time period of earth would decrease
• D. Length of day would increase

Answer 1

Answer: (D)

Length of day would increase

Consider the problem,

In the case of mineral,

coverage area $\left(r\right)$ increases

Therefore, Inertia $I=M{r}^2$

If $r$ increases, then $I$ increases

and, also $L=I\omega$

$L$ is conserved, then if $I$ increases, $\omega$ decreases.

And also, $\omega =\frac{2\pi }{T}$

If $\omega$ decreases, then Time period $\left(T\right)$ increases.

Therefore, length of the day increases.