Collapse the star had a mass of 2 times the mass of the sun and a radius the same as the sun. before the collapse it rotates once every 10 days. after the collapse it has not lost any mass but now has a radius of only 10 km. what is its rotation rate in rev/s after the collapse

0.2 milisecond

Explanation:

Let the mass of sun is M

mass of star = 2 M

initial radius of the star, R = radius of sun = 7 x 10^5 km

initial time period, T = 10 days

final radius, R' = 10 km

mass remains same.

As no external torque is acting on the star so its angular momentum remains constant.

So, Angular momentum before collapsing = Angular momentum after collapsing

I x ω = constant

T' = 2.04 x 10^-9 days

T' = 0.2 milisecond

a solenoid is created by wrapping a l = 90 m long wire around a hollow tube of diameter d = 4.5 cm.   the wire diameter is d = 0.9 mm.   the solenoid wire is then connected to a power supply so that a current of i = 9 a flows through the wire.

randomized variablesl = 90 m

d = 4.5 cm

d = 0.9 mm

i = 9 a                                          

write an expression for the number of turns, n, in the solenoid. you do not need to take into account the diameter of the wire in this calculation.

calculate the number of turns, n, in the solenoid.

write an expression for the length of the solenoid (l2) in terms of the diameter of the hollow tube d.

calculate the length of the solenoid (l2)   in meters.

calculate the magnitude of the magnetic field at the center of the solenoid in teslas.

explanation:

terd muffin is the correct answer