Circular motion and gravity help

AI Thread Summary
To solve the first problem regarding the star's rotation period after its diameter shrinks, the conservation of angular momentum can be applied, as the mass distribution remains uniform. The second problem involves analyzing a pulley system with two masses, where the tension forces and gravitational forces must be compared. Key relationships between the tensions (T1, T2, T3) and the gravitational forces acting on the masses need to be established to understand the system's dynamics. The discussion emphasizes the importance of using appropriate equations and concepts related to circular motion and gravitational forces. Clarification on the use of templates and problem separation is also highlighted as essential for effective problem-solving.
katiegerster
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Homework Statement



1. The mass of a star is 1.830×1031 kg and it performs one rotation in 37.30 days. Find its new period (in days) if the diameter suddenly shrinks to 0.850 times its present size. Assume a uniform mass distribution before and after.

2. A pulley with mass Mp and a radius Rp is attached to the ceiling, in a gravity field of 9.81 m/s2 and rotates with no friction about its pivot. Mass M2 is larger than mass m1. The quantities Tn and g are magnitudes. Choices: true, false, greater than, less than, or equal to.

The C.M. of Mp+M1+M2 does not accelerate.
T1 is ... T2
m1g + M2g + Mpg is ... T3.
T3 is ... T1 + T2
T2 is ... M2g.
The magnitude of the acceleration of M2 is ... that of m1.

Homework Equations



T=mg

The Attempt at a Solution



do not know how to go about solving either of these :(
 
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Don't post two different problems in one thread. I am not sure this is strictly against the rules, but it makes things very confusing.
 
the second question is just conceptual so i had hoped it wouldn't make things to confusing, I am sorry
 
It may be, but you ignored the template requirements for the first question.
 
i know, its because i don't even know what equation to use for it, no one can seem to figure out how to solve it...
 
What properties of rotating bodies do you know about, especially those that are conserved?
 

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