What are the moment of inertia, angular speed, and angular kinetic energy?

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To find the moment of inertia of the electron in circular motion, the formula I = m*r^2 is used, where m is the mass of the electron and r is the radius of the orbit. Angular speed can be derived from the angular momentum equation L = I*W, allowing for the calculation of W once I is known. The angular kinetic energy is calculated using the formula KE = 0.5*I*W^2. The discussion emphasizes the need to first determine the speed of the electron to proceed with these calculations. Understanding these relationships is crucial for solving the problem effectively.
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Homework Statement



an electron (mass 9.11*10^-31kg) moves in a circular orbit around nucleus of mass 1.67*10^-27kg. if the radius of orbit is 5*10^-11 meters and the angular momentum is 1.05*10^-34 kg*m^2/s

find moment of inertia
angular speed
angular kinetic energy

Homework Equations





The Attempt at a Solution



to find I, we need W (angular velocity). How do i find this if i just have 2 masses and radius?
 
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well can you find speed of electron?
 
gamer1319 said:
to find I, we need W (angular velocity). How do i find this if i just have 2 masses and radius?

What's the moment of inertia of a point mass at a distance r from the center of rotation?
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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