Circular motion and gravity help

In summary, the first conversation is about finding the new period of a star with a mass of 1.830×1031 kg and a rotation period of 37.30 days if its diameter shrinks to 0.850 times its original size. The second conversation involves a pulley system and the comparison of different quantities such as tension and acceleration. The student is unsure of how to solve the problems and is seeking help.
  • #1
katiegerster
13
0

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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  • #2
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.
 
  • #3
the second question is just conceptual so i had hoped it wouldn't make things to confusing, I am sorry
 
  • #4
It may be, but you ignored the template requirements for the first question.
 
  • #5
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...
 
  • #6
What properties of rotating bodies do you know about, especially those that are conserved?
 

Related to Circular motion and gravity help

1. How does circular motion differ from linear motion?

Circular motion is the motion of an object along a circular path, while linear motion is the motion of an object in a straight line. In circular motion, the direction of the object's velocity is constantly changing, while in linear motion, the velocity remains constant.

2. What is the role of gravity in circular motion?

Gravity is responsible for keeping objects in circular motion. In circular motion, there must be a force acting towards the center of the circle in order to maintain the object's circular path. This force is provided by gravity, which is constantly pulling the object towards the center of the circular path.

3. How does the mass of an object affect circular motion?

The mass of an object does not affect the circular motion itself, but it does affect the amount of force needed to keep the object in circular motion. Objects with larger masses require more force to maintain their circular path, while objects with smaller masses require less force.

4. Can circular motion occur without gravity?

No, circular motion cannot occur without gravity. As mentioned earlier, gravity is necessary for providing the centripetal force that keeps objects in circular motion. Without gravity, the object would continue in a straight line instead of following a circular path.

5. What is the relationship between centripetal force and circular motion?

Centripetal force is the force that acts towards the center of a circular path and is necessary for maintaining circular motion. The greater the centripetal force, the faster the object will move in its circular path. If there is not enough centripetal force, the object will move out of its circular path and into a straight line.

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