# Rotating a Professor on a Turntable

Not what you're looking for?

Hi

I need you help for two questions.

1. A professor steps onto a stationary turntable while holding a rotating bicycle wheel that is rotating with an angular velocity of 15 rad/s pointing upward. The wheels axis of rotation goes through the axis of the turntable. The rotational inertia of the wheel is 1.5 kg m^2 and the combined rotational inertia of the professor and the turntable about the turntable's axis is 9.0 kg m^2. The professor flips the bicycle wheel so that it is still rotating with the same angular velocity, but pointing downward. How fast will this cause the professor and the turntable to rotate?

2. How much work is required to bring a 2.00-kg mass, 4.00-cm radius uniform sphere from rest to a rotational speed of 30.0 revolutions per second about an axis through its center?

Thank you for your help.

##### Purchase this Solution

##### Solution Summary

The solution uses the laws of the conservation of angular momentum to solve this problem of rotation, explaining the methods in clear, easy-to-follow steps aided by short written explanations.

##### Solution Preview

1)

Moment of inertia of the wheel I1 = 1.5 kg.m^2

Moment of inertia of the professor + turntable I2 = 9.0 kg.m^2

Initial angular velocity of the wheel w1 = 15 rad/s (pointing upward)

Let us assume before flipping the angular velocity of the professor+turntable be 'wo'

Therefore, by the law of conservation of angular momentum,

I1*w1 = ...

###### Education

- BEng, Allahabad University, India
- MSc , Pune University, India
- PhD (IP), Pune University, India

###### Recent Feedback

- " In question 2, you incorrectly add in the $3.00 dividend that was just paid to determine the value of the stock price using the dividend discount model. In question 4 response, it should have also been recognized that dividend discount models are not useful if any of the parameters used in the model are inaccurate. "
- "feedback: fail to recognize the operating cash flow will not begin until the end of year 3."
- "Answer was correct"
- "Great thanks"
- "Perfect solution..thank you"

##### Purchase this Solution

##### Free BrainMass Quizzes

##### Variables in Science Experiments

How well do you understand variables? Test your knowledge of independent (manipulated), dependent (responding), and controlled variables with this 10 question quiz.

##### Classical Mechanics

This quiz is designed to test and improve your knowledge on Classical Mechanics.

##### Basic Physics

This quiz will test your knowledge about basic Physics.

##### Intro to the Physics Waves

Some short-answer questions involving the basic vocabulary of string, sound, and water waves.

##### The Moon

Test your knowledge of moon phases and movement.