Rotating half cylinder energy and power calculation

In summary, the conversation discusses an ocean engineer's desire to quantify energy and relate it to potential power output. The engineer provides details of the object's mass, length, radius, and rotational kinetic energy, and asks for confirmation on their calculations. They also inquire about a meaningful way to relate the energy to power, considering a conversion efficiency and the constant motive force. The response notes that the engineer's approach is correct but clarifies that 60 rpm is actually 2*pi rad/s and provides an alternative calculation for the energy.
  • #1
crf59
1
0
Hi folks,

I'm an ocean engineer who's getting old and slow. If I have a half-cylinder mass on a shaft where I'd like to be able to quantify energy (which I think I have right) and then have some way of relating that to potential power output.

What I have so far:
m=18.6 kg
Length=0.305m
radius=0.07m
Mass moment of inertia (I) = 0.5mr^2
Rotational KE (Er) = 0.5Iw^2
w=60rpm=0.159 rad/s

I calculate the Er as 0.00747J

Does this jive? Is there any meaningful way of relating that to power? I do not have a load value (yet), so am just trying to understand what this might be in terms of power if I use some conversion efficiency (thinking alternator load). I am assuming the same motive force that accelerated it to 60 rpm is constant (in some sort of resonance). If I have my calcs/assumptions wrong so far, please correct.
 
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  • #2
Welcome to Physics Forums.

You're general approach is correct. However, 60 rpm is actual 2*pi rad/s. I get 0.90 J for the energy. (I=0.046 kg-m2)
 

1. What is the purpose of calculating energy and power in a rotating half cylinder?

The purpose of calculating energy and power in a rotating half cylinder is to understand the amount of energy being generated and the rate at which it is being produced. This can be useful in various industries such as renewable energy, engineering, and physics.

2. How is energy calculated in a rotating half cylinder?

Energy in a rotating half cylinder can be calculated by multiplying the rotational speed of the cylinder (in radians per second) by the moment of inertia and the square of the radius.

3. What factors affect the energy and power output of a rotating half cylinder?

The energy and power output of a rotating half cylinder can be affected by various factors such as the rotational speed, moment of inertia, radius of the cylinder, and the density and viscosity of the fluid inside the cylinder.

4. How is power calculated in a rotating half cylinder?

Power in a rotating half cylinder can be calculated by multiplying the torque (force applied to rotate the cylinder) by the angular velocity (rotational speed in radians per second).

5. Can the energy and power output of a rotating half cylinder be increased?

Yes, the energy and power output of a rotating half cylinder can be increased by increasing the rotational speed, reducing the moment of inertia, and using a more dense and less viscous fluid inside the cylinder. Additionally, optimizing the design of the cylinder and its components can also increase its energy and power output.

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