Calculate Angular Velocity after Star's Diameter Decrease

Click For Summary
SUMMARY

The discussion focuses on calculating the new angular velocity of a star after its diameter decreases to 0.17 times its original size. Given the star's mass of 1.1e31 kg and initial angular velocity of 1.40×10-7 rad/s, the conservation of angular momentum is applied using the formula I1w1 = I2w2. The moment of inertia for a solid sphere is utilized, confirming that the radius 'r' cancels out in the calculations, allowing for the determination of the new angular velocity without needing its specific value.

PREREQUISITES
  • Understanding of angular momentum conservation
  • Familiarity with moment of inertia for solid spheres
  • Basic knowledge of angular velocity and its units
  • Ability to manipulate algebraic equations
NEXT STEPS
  • Study the derivation of the moment of inertia for various shapes
  • Learn about the implications of angular momentum conservation in astrophysics
  • Explore the effects of mass distribution on rotational dynamics
  • Investigate real-world applications of angular velocity calculations in celestial mechanics
USEFUL FOR

Astronomy students, astrophysicists, and anyone interested in the dynamics of rotating celestial bodies will benefit from this discussion.

Naldo6
Messages
102
Reaction score
0
The mass of a star is 1.1e31 kg and its angular velocity is 1.40×10-7 rad/s. Find its new angular velocity if the diameter suddenly shrinks to 0.17 times its present size. Assume a uniform mass distribution before and after. [Icm for a solid sphere of uniform density is 2/5 mr^2].

i have to use I1w1=I2w2

it is (2/5)mr^2w1=(2/5)mr^2w2 and find out my w2

but i have all the data unless the r.

what i should put in r?...
 
Physics news on Phys.org
Don't put anything in for r. Leave it 'r'. If the initial radius is r then the final radius is 0.17*r. The r itself will cancel. If they don't give you a value for a number, it's a pretty sure bet that you don't even need to know it since it will cancel out from both sides of the equation.
 

Similar threads

How Does Angular Momentum Conservation Affect Asteroid Collision Dynamics?
  • · Replies 335 ·
12
Replies
335
Views
17K
How Do You Correctly Cancel Angular Momentum in Physics Problems?
  • · Replies 3 ·
Replies
3
Views
2K
Solve Angular Velocity & Acceleration - Dimensional Analysis
  • · Replies 3 ·
Replies
3
Views
2K
The final velocity of a ball rolling while slipping.
  • · Replies 40 ·
2
Replies
40
Views
5K
System of two wheels of different sizes with an axle through their centers
  • · Replies 67 ·
3
Replies
67
Views
5K
Help with Angular Velocity True-False Question
  • · Replies 12 ·
Replies
12
Views
2K
Angular velocity of cylinders after slipping over each other
  • · Replies 2 ·
Replies
2
Views
3K
Angular velocity and angular acceleration of a turbine
  • · Replies 17 ·
Replies
17
Views
3K
What is the final angular velocity of each cylinder
  • · Replies 1 ·
Replies
1
Views
2K
New Angular Velocity of Star with Diameter Shrink to 0.17 Times
  • · Replies 3 ·
Replies
3
Views
3K