# Qn on Rotational Kinetic Energy

1. Mar 31, 2010

### lavieenrose

1. The problem statement, all variables and given/known data
Crab Nebula releases energy at a rate of 5x1031 W, obtaining its energy from the rotational kinetic energy K of a neutron star at its centre.
Period of neutron star's rotation = 0.0331s. T increases by 4.22 x 10-13s per second.

What is the moment of inertia of the neutron star?

2. Relevant equations
dK/dt = -(4$$\pi$$2I/T3) (dT/dt)
This was the first part of the question which I managed to prove already.
*Note: the pi is not supposed to be in superscript.

3. The attempt at a solution
I equated the power of the star to the above differential equation. Solving for I should be quite easy, but somehow my answer (1.1x 1038) is different from the answer provided (1.1 x 1030).

2. Apr 1, 2010