# Concept of Gravitation

**Question**

Find the minimum !!omega!! such that man feels weightless.

(a) !!(2/3)sqrt(g/R)!!

(b) !!(4/3)sqrt(g/(3R))!!

(c) !! sqrt(g/(3R))!!

(d) !!(2/3) sqrt(g/(3R))!!

**Solution**

For weightless

The contact force by surface on man !!(N)!! will be zero. So, centrifugal force will be equal to !!mg!!.

!!=> m (omega)^2 (3R)= mg!!

!!=> omega = sqrt(g/(3R))!!