A star rotates with a period of 37 days about an axis through its center. The period is the time interval required for a point on the star's equator to make one complete revolution around the axis of rotation. After the star undergoes a supernova explosion, the stellar core, which had a radius of 2.0 ✕ 104 km, collapses into a neutron star of radius 6.1 km. Determine the period of rotation of the neutron star. SOLUTION Conceptualize The change in the neutron star's motion is similar to that of the skater described earlier in the textbook, but in the reverse direction. As the mass of the star moves closer to the rotation axis, we expect the star to spin Correct: Your answer is correct. . Categorize Let us assume that during the collapse of the stellar core, (1) no external torque acts on it, (2) it remains spherical with the same relative mass d

T = 1.1285 10⁻² day

Explanation:

For this exercise the forces in the premiere are internal, so the angular momentum is conserved

         L₀ = I₀ w₀

         L  = I w

         L₀ = L

         I₀ w₀ = I w

Angular velocity and period are related

         w₀ = 2π / T₀

         w = 2π  / T

The moment of inertia of a sphere is

       I₀ = 2/5 M R²

       I = 2/5 m r²

If we assume that the mass of the star does not change in the transformation

We substitute

         2/5 M R² 2π/T₀ = 2/5 M r² 2π/ T

          R² /T₀ = r² / T

          T = (r / R)² T₀

          T = (6.1 / 2.0 104) 37

          T = 1.1285 10⁻² day

okay i have so many questions. but the big one here is: um wt..f is this mess? ?

elly's long hair:

a. if the salon only takes cash, then this isn't the problem. it doesn't matter how much she has in her checking account.   she can't get a haircut until she has the cash.

b. if she has overdraft protection, then there's no problem.   she can go ahead and write a check that her account can't cover, then sometime later, pay the bank some outrageous usury for loaning her a few bucks for a few days, but with beautiful hair.

c. if elly has some principles, and doesn't want to write a bad check, then now she has a problem.   her desire for the new hairstyle is in conflict with her honesty and integrity.

d.   if the bank will not process a check she writes, then even if she had a million $$ in her account, she couldn't use any of it.   the amount she has in her account is not the problem.   and if i may suggest, she might as well close her checking account, and put the money where it'll work for her.   it's not doing her a bit of good in a checking account, since she can't write any checks.

justin can't pay the full balance:

a. he can't even handle the credit limit he has now.   under no circumstances should he ask for a higher limit.

b.   he can ask for the grace period to be extended.   but that's no solution, the bank will almost certainly refuse anyway, and there are much better options.   he knew the rules of his credit card when he started using it.

c.   he definitely should pay the interest on the balance, plus as much of the balance as he can cover at the same time.

d.   he definitely should pay the minimum otherwise they could shut down his card.   he should also pay as much more as he possibly can.   he should also remember the awkward situation he's in, stop buying stuff on credit that he can't afford, and avoid adding any more debt.

i'd say that justin's best best option isn't on this list of choices.   what he has to do:   pay as much as he can at least the minimum payment plus as much more as he can and then avoid adding more debt.