Question

The period of rotation of the earth so as to make any object weight-less on its equator is

• A. 84 min
• B. 74 minutes
• C. 64 minutes
• D. 54 minutes where M and r are the mass and radius of earth.

Answer 1

Answer: (A)

84 min

Answer 2

Put g_e = 0, in the expression

g_e = g₀ - rω² ⇒ ω = $\sqrt{\frac{g_{0}}{r}}$

⇒ T = 2π $\sqrt{\frac{r}{g_{0}}}$, putting r = 6.4 × 10⁶m and g₀ = 9.8 m/sec²,

we obtain, T = 84 min

Therefore (1)