The law of universal gravitation:

a. produces stars and planets
b. produces stars but not planets
c. produces planets but not stars
d. cannot produce neither stars or planets

if anyone could me that would be great! (sorry if its not in correct subject i believe it is, though)

Awind turbine is rotating counterclockwise at 0.5 rev/s and slows to a stop in 10 s. its blades are 20 m in length. (a) what is the angular acceleration of the turbine? (b) what is the centripetal acceleration of the tip of the blades at t=0s? (c) what is the magnitude and direction of the total linear acceleration of the tip of the blades at t=0s?