Understanding the Formula of Power: Torque x Angular Velocity Explained

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Power is defined as the product of torque and angular velocity, expressed mathematically as Power = torque x angular velocity. The units for power are indeed Nm/s, while torque multiplied by angular velocity yields Nm(rad/s). The confusion arises from the nature of radians, which are considered dimensionless, allowing for the cancellation of units in the formula. Thus, the formula is correct when using radians for angular velocity. Understanding this relationship clarifies the dimensional analysis of power in rotational systems.
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Homework Statement


i was told that Power = torque x (angular velocity)

Homework Equations

The Attempt at a Solution


I found that power has unit of Nm/s,
torque x (angular velocity) has unit of Nm(rad/s), is the formula given wrong?
 
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chetzread said:

Homework Statement


i was told that Power = torque x (angular velocity)

Homework Equations

The Attempt at a Solution


I found that power has unit of Nm/s,
torque x (angular velocity) has unit of Nm(rad/s), is the formula given wrong?
Angles do not have a dimension in the way that mass, time, etc. do.
Consider e.g. that a circular arc of radius r and angle θ has length rθ.
Nevertheless, they do have units, and the unit "radian" is chosen in such a way that you do not need to include a constant in the rθ formula. It turns out that this also means you do not need a constant in the power formula if radians are used in the angular velocity.
 
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Or, angles are dimensionless.
 
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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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