How Do You Calculate the Kinetic Energy of a Spinning Bicycle Wheel?

  • Thread starter bigbuck
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In summary, the conversation discusses the calculation of kinetic energy for a spinning bicycle wheel. The person has followed the equations but is unsure about the relationship between the units used. They mention that they believe the kinetic energy should be in joules and provide their calculated answer. Another person points out that the angular velocity should be squared in the equation and confirms that the units used are correct. The first person expresses their gratitude for the clarification.
  • #1
bigbuck
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While i have done the work and believe i have followed the equations, I'm not confident of my answer as I don't understandt the relationship between the units I am using. While I am pretty sure KE shoudl be in joules. I am guessing in the end.

the question:
Calculate the kinetic energy of a 1.00kg bicycle wheel with a diameter of 72.0cm when it is spinning about its axle at 180rpm. Assume that all the mass of the wheel is concentrated at its perimeter.

my answer:
KE=.5*I*om^2
I=m*r^2 1.00kg*(.360m)^2 = .130kg*m^2
omega = 180rev/m*6.28rads/60sec=18.84rad/s
.5*.130kg*m^2*18.84rads/s=1.22J

thanks
 
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  • #2
You forgot to square the angular velocity. The units are fine.
 
  • #3
thanks!
much appreciated
 

1. What is rotational dynamics?

Rotational dynamics is a branch of physics that studies the motion of objects that are rotating or moving in a circular path. It involves the application of Newton's laws of motion to rotational motion and the principles of torque and angular momentum.

2. How is rotational dynamics different from linear dynamics?

In linear dynamics, the focus is on the motion of objects in a straight line, while in rotational dynamics, the focus is on the motion of objects around a fixed axis. Additionally, rotational dynamics takes into account the rotational inertia of objects, which is not a factor in linear dynamics.

3. What are some real-world examples of rotational dynamics?

Some examples of rotational dynamics in everyday life include the motion of a spinning top, the rotation of a bike wheel, and the movement of a merry-go-round. It also plays a role in the motion of planets around the sun and the rotation of the Earth on its axis.

4. How is rotational dynamics used in engineering?

Rotational dynamics is used in engineering to design and analyze various mechanical systems, such as car engines, turbines, and gears. It is also important in understanding the stability and control of aircraft and spacecraft.

5. What are the applications of rotational dynamics in sports?

Rotational dynamics has many applications in sports, particularly in activities that involve spinning or rotating movements, such as gymnastics, figure skating, and diving. Understanding rotational dynamics can help athletes improve their technique and performance.

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