(100 points!) A star of radius R1 rotates every 20 days. The star suddenly collapses to a radius R2, which is smaller by a factor of 10000 (R2=R1/10000) without losing mass.

a. What is the new angular velocity of the star? You may assume that the moment of inertia of the star is that of a solid sphere (I=(2/5)mR^2)?

b. What is the ratio of the kinetic energy before and after the collapse (KEf/KEi)?

A2 kg ball travellng to the right with a speed of 4 m/s collidees with a 5 kg ball traveling to the left with a speed of 3 m/s. take right to be the positive direction. what is the total momentum of the two balls before they collide? what is the total momentum of the two balls after they collide?

What are the starting materials for nuclear fission? two small nuclei two large nuclei a neutron and a large nucleus a neutron and a small nucleus

Consider the growth of a 20-nm-diameter silicon nanowire onto a silicon wafer. the temperature of the wafer surface is maintained at 2400 k. assume the thermal conductivity of the silicon nanowire is 20 wm-1k-1 and all its surfaces including the tip are subjected to convection heat transfer with the coefficient h = 1×105 wm-2k-1 and t∞ = 8000 k. when the nanowire grows to l = 300 nm, what is the temperature of the nanowire tip (t (x =