Question

If the earth reduces it's radius by half, what would be the duration of day?

Answer 1

conservation of angular momentum
Iw =constant for solid
2/5 mR²w= constant
wR²= constant
2πfR² = constant
R²/T = constant
so, T is directly proportional to square of radius
Thus if radius is decreased to half then,
T'= T/4
which is 24/4
time period will be 6 hours.