Calculating Rotation Period of a Collapsing Interstellar Cloud

In summary, a uniform, spherical cloud of interstellar gas with a mass of 2.03×1030 kg and radius of 1.03x1013m collapses to form a star with a radius of 7.03x108m. The star's rotation period can be calculated using the moment of inertia equation and is found to be 6.7×10-3 years or approximately 2.42 days. The provided answer of 88.9 minutes may be incorrect.
  • #1
gex
37
2

Homework Statement


A uniform, spherical cloud of interstellar gas has mass 2.03×1030 kg and radius 1.03x1013m and is rotating with period 1.43×106 years. The cloud collapses to from a star 7.03x108m in radius. Find the star's rotation period.

Homework Equations


I1ω1=I2ω2
Θ=ωt

The Attempt at a Solution


Determine ω:[/B]
2π=ω(1.43×106)
ω=4.4×10-6
Use Moment of Inertia Equation: I=2/5(mr2)
I1=8.61×1055
I2=4.01×1047
∴ ω2=944.74 rad/year
Determine t:
Θ=ωt
∴ t=Θ/ω
=2π/944.74
=6.7×10-3
=2.42 days

Hey guys, I've been trying to do this homework question for a while now but I can't seem to get to the answer of 88.9 minutes. Any help getting there is much appreciated. Thank you all in advance.
 
Physics news on Phys.org
  • #2
I agree with your method and answer.
 
  • #3
Wow odd. I will ask the teacher about the provided answer being incorrect then, thank you for shedding some light on this haruspex.
 

1. What is rotational motion?

Rotational motion is the movement of an object around an axis or fixed point. It is also known as circular motion and can be seen in objects such as wheels, planets, and gears.

2. What is the difference between linear and rotational motion?

Linear motion involves movement in a straight line, while rotational motion involves movement around an axis. Linear motion can be described using displacement, velocity, and acceleration, while rotational motion can be described using angular displacement, angular velocity, and angular acceleration.

3. How is rotational motion measured?

Rotational motion is measured using units such as radians, revolutions, and degrees. Angular displacement is measured in radians, while angular velocity is measured in radians per second. Angular acceleration is measured in radians per second squared.

4. What is torque and how does it affect rotational motion?

Torque is a measure of the force that causes an object to rotate around an axis. It is calculated by multiplying the force applied to an object by the distance from the axis of rotation. Torque affects rotational motion by causing objects to rotate and change their angular velocity.

5. What are some real-life examples of rotational motion problems?

Some examples of rotational motion problems include the motion of a spinning top, the rotation of a bicycle wheel, and the movement of a car's wheels. Other examples include the rotation of a Ferris wheel, the spinning of a ball on a string, and the swinging of a pendulum.

Similar threads

Energy and power supplied by a bicyclist
    • Introductory Physics Homework Help
Replies
8
Views
3K
Calculating Radial Acceleration of a Rotating Wheel
    • Introductory Physics Homework Help
Replies
2
Views
3K

Hot Threads

Recent Insights

Back
Top