Circular motion and gravity help

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Homework Help Overview

The discussion revolves around two problems related to circular motion and gravity. The first problem involves calculating the new period of a star after a change in diameter, while the second problem concerns a pulley system with varying masses and tensions.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • Participants express uncertainty about how to approach the first problem, particularly regarding the relevant equations. The second problem is noted as more conceptual, prompting discussions about the properties of rotating bodies and conservation principles.

Discussion Status

Some participants are questioning the appropriateness of posting two different problems in one thread, while others are attempting to clarify the requirements and properties relevant to the problems. There is a recognition of confusion regarding the first problem's template requirements.

Contextual Notes

Participants note the lack of clarity in the original poster's submission, particularly in adhering to the expected format for homework questions. There is also an acknowledgment of the complexity of the problems presented.

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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