# Harry Potter's Physics on a Rotating Turntable

• a.303
In summary, a turntable with a moment of inertia (I) of 400 kgm2/s and a radius of 2m is rotating at an angular velocity (omega) of 2 rad/s. Harry Potter (HP) of mass 60 kg and Tri-Wizard Cup (TWC) of mass 20 kg are diametrically opposite to each other on the rim of the turntable. HP's tangential velocity is 4 m/s. When HP falls off tangentially, the new omega, I, and angular momentum (L) of the turntable+TWC system are 2.5 rad/s, (m1+m2)4*c, and (m1+m2)*2*c respectively.
a.303

## Homework Statement

A turntable with I=400 kgm2/s and radius 2m is rotating at omega=2 rad/s. Harry Potter (HP) of mass 60 kg and Tri-Wizard Cup (TWC) of mass 20 kg are diametrically opposite to each other on the rim of the turntable.
a) What is HP's tangential velocity?
b) HP falls off tangentially. What is the omega, I and L of the turntable+TWC system?
c) HP jumps off radially from the rim. What is omega, I, L of the turntable+TWC system?
d) HP jumps off such that his tangential velocity is 2 m/s with respect to Earth. What is the omega, I and L of the turntable+TWC system?
e) HP jumps off such that his tangential velocity is 6 m/s with respect to Earth. What is the omega, I, and L of the turntable+TWC system?
f) HP jumps up high vertically. What is the omega, I and L of the turntable+TWC system?
g) HP starts walking along the rim of the turntable at 2 m/s w.r.t. Earth. What is the new omega of turntable+TWC system as he walks?
h) HP randomly walks toward the TWC and stops very close to it. What is the omega, I and L of the turntable+TWC+HP system?
i) HP touches the TWC which turns out to be a port-key. Both HP and TWC disappear. What is the new omega, I and L of the turntable? Assume zero torque.

L=rpsin(theta)
L=I*omega
p=mv
I=cMR2

## The Attempt at a Solution

b)I initial= (m1+m2)4*c
I final= 400- .5*M*R2=340 kgm2/s

a.303 said:
b)I initial= (m1+m2)4*c
What is c? What about the I of the turntable?
a.303 said:
I final= 400- .5*M*R2=340 kgm2/s
How can the MoI of the TWC system be less than that of the turntable alone?
What about the angular momentum (L) of the system after HP leaves?

Tangental velocity is wr which is 4

Rohan1997 said:
Tangental velocity is wr which is 4
a.303 already got that (and better, included units).

## 1. What is "Harry Potter on a Turntable"?

"Harry Potter on a Turntable" refers to a viral video that combines the world of Harry Potter with the concept of a turntable, resulting in a mesmerizing display of the movie's characters rotating on a spinning platform.

## 2. How was "Harry Potter on a Turntable" created?

The video was created using a technique called "rotoscoping," where individual frames from the movie were traced and then combined with the rotating turntable effect to create the illusion of movement.

## 3. Who created "Harry Potter on a Turntable"?

The video was created by YouTube user "davidmichaelbennett," who is known for his creative and unique videos that often combine different elements and concepts.

## 4. Is "Harry Potter on a Turntable" an official Harry Potter production?

No, the video is not an official production of the Harry Potter franchise. It was created by a fan and is not endorsed or affiliated with Warner Bros. or J.K. Rowling.

## 5. Are there any other similar videos or projects like "Harry Potter on a Turntable"?

Yes, there are many other videos and projects that use the same concept of combining popular media with the turntable effect. Some examples include "Disney Princesses on a Turntable" and "Game of Thrones on a Turntable."

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