Rotational Kinematics, please help me understand.?

Question

(Again, not using this for homework but studying purposes, thanks) Also, I got the answer to the first part, just wondering about the second part.

A star has a mass of 1.40X10^30kg and is moving in a circular orbit about the center of its galaxy. The radius of the orbit is 3.9x10^4 light years (1 light year = 9.5 X 10^15m), and the angular speed of the star is 2.1X10^-15 rad/s. (a) Determine the tangential speed of the star. (b) What is the magnitude of the net force that acts on the star to keep it moving around the center of the galaxy?

The tangential speed = 7.8X10^5 m/s
and assuming you need the radius for (b), it works out to be 3.7X10^20m

Answer 1

Tangential speed looks great. I got the same thing.

I just got 2.3 x10^21 N for the Force for b. I think I did it right, but you can double check.

Radial Force = m*v^2/r

>>>>>>>>>>>>>>>>

I came back and as a double check did it again using the formula

Radial Force = m * w^2 * r
where w = angular acceleration.

Got the same number.

Good luck.