I think the force of spinning it can only hold for so long and because of gravitys pressure.(i hope i helped) :)
Answer:

Explanation:
The acceleration of the train is given by:

where:
u = 5 m/s is the initial velocity of the train
v = 45 m/s is the final velocity of the train
t = 8 s is the time taken for the train to increase the velocity
Substituting numbers into the formula, we find

Velocity = The speed and direction that an object is moving at
If a main sequence star is cooling and expanding, it is entering the red giant stage. This means that the star has burned up all of it's hydrogen and is now starting to burn its helium making it cooler.