Lecture 19: Rotating Rigid Bodies - Moment of Inertia - Parallel Axis and Perpendicular Axis Theorem - Rotational Kinetic Energy - Fly Wheels - Neutron Stars - Pulsars
recorded by: Massachusetts Institute of Technology, MIT
published: Oct. 10, 2008, recorded: October 1999, views: 76474
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1. Angular Acceleration in Circular Motion:
An object in circular motion can experience a tangential acceleration (resulting in a change of its speed). Similarities between equations for linear motion and rotational motion are drawn.
2. Kinetic Energy of Rotation - Moments of Inertia:
The kinetic energy of rotation of a disk is derived and related to its moment of inertia and angular velocity. The moment of inertia depends upon the shape and mass of an object; it differs for different axes of rotation.
3. Parallel Axis and Perpendicular Axis Theorems:
The Parallel Axis theorem is very useful for calculating the moment of inertia about an axis offset from the center of mass. The Perpendicular Axis theorem is useful for thin objects.
4. Energy Management with Flywheels:
A scenario is explored where the potential energy of a car coming down a mountain is stored in a flywheel (while stepping on the brakes) rather than dissipated into heat. The rotational kinetic energy of the flywheel can, in principle, at a later time be used to increase the car's speed when needed. A demonstration shows how rotational energy in a flywheel gets converted into linear motion of a toy car.
5. Flywheels at MIT's Magnet Lab:
A pair of very massive flywheels rotating at 6 Hz are used to convert rotational kinetic energy into magnetic energy and vice versa for energy storage.
6. Rotational KE in Planets and Stars:
The rotational kinetic energy of the sun and Earth due to their spin are presented, along with data from the Crab pulsar. The Crab pulsar, with a spin period of 33 ms, is spinning down; its spin period is increasing by 36.4 nanoseconds/day. The radiated power (in the form of radio waves, light, X-rays and gamma-rays) results in a loss of rotational kinetic energy. In other words, rotational KE is converted to electromagnetic radiation.
7. Slides of MIT's Flywheel and the Crab Nebula:
Slides are shown of the Flywheels in MIT's Magnet Lab, and of the Crab Nebula (home of the Crab Pulsar). Stroboscopic pictures show that the Crab Pulsar blinks on and off in optical light as it rotates about its spin axis. An X-ray image of the Crab Nebula made with the Chandra Observatory is also shown.
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very clear explanation, Now i have better understanding because of all these videos. Thanks
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This professor is excellent at lectures. He is very clear - worth every penny of tuition to register for his class, I'm sure. I will now be watching his videos to supplement my own professor's lectures.
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Thank you so much for explaining rotational kinetic energy.
I am using this information to better study the dead wave patterns in various states of viable and non viable consciousness. Dead Waves can amplify during sensory deprivation when triggered by certain constants. This has helped me to better understand the thresholds and parallels between the Universe and that of evolutionary data currently presented.
I believe the universe is a semi complete and identical parallel, and its patterns can be presented not only in the world but in the very research of brain function itself.
Thank you Again... I am so glad you are here for us.
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01 Pl explain --- Differentiation between Moment of Inertia & Polar Moment of Inertia.
02 Pl explain --- Differentiation between Mass Moment of Inertia & Mass Polar Moment of Inertia.
For a series of parallel rotational axises, about which axis the body is rotating, the body has the smallest rotational inertia?
i would be glad if you could give me a solution to this problem.thank u
Ahhh. Makes sense now. Need to find something a bit more advanced though, but great foundation.
thanks alot, i feel like i am an MIT student now
I am a physics teacher. I always admired Prof. Walter H. G. Lewin of MIT, his popular lecture on Rainbow is simply superb. I learn many tips to make my lecture interesting to the students.
the handle of a wheel is 90 degree for 5 seconds. the wheel has a constant angular acceleration of 1 rad/second square. through what angle will the wheel have rotated after 10 seconds?
Lectures are Excellent. It helps in understanding Physics excellently. Prof Lewin prepared the chapters in a different meticulous approach which his viewers becomes spell bound with charm and interest. Many many sincere thanks to him. Specially now a days in developing countries there exists a dearth of Good Physics teachers.These lectures will help immensely to young and aspiring students who want to learn such a wonderful branch of Science, from a Teacher like him.
He talks/refers to which book during his lectures anyone knows ?
how can i find solution of question about this chapter.
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