4.0 Additional Questions: 1. At the center of the Crab Nebula is a neutron star; it has a diameter of 20 Km; its mass is approximately 1.4 times the mass of the Sun; and its rotation period is about 33 msec. What is the centripetal acceleration at the equator of this star? Express also in terms of the g for earth. ( Mass of the Sun is: 1.99 x 1030 Kg ) 2. The gravitational acceleration at the surface of a sphere of radius r and mass M is given by: GM g = (8 What is the gravitational acceleration at the surface of the Crab Nebula's neutron star? How does that compare with the centripetal acceleration calculated in question 1 above? Calculate the ratio: R = y crab a crab ( The gravitational constant: G = 6.67 x 10-11 Nm /Kg= )