### Re: Anybody wants to talk PHYSICS?

#1
I'm a physics undergrad, about to take the General Physics III exam, also called Modern Physics.

I was wondering if anybody was up for some nerdy chat, maybe ask a couple questions and put me through the wringer. I do love to reply to idiotically complex questions, because they give me inspiration and motivation to study new topics and dig up information. Also, it will help me prepare for the exam better.

I'll wait here, don't make me feel too alone!

I was wondering if anybody was up for some nerdy chat, maybe ask a couple questions and put me through the wringer. I do love to reply to idiotically complex questions, because they give me inspiration and motivation to study new topics and dig up information. Also, it will help me prepare for the exam better.

I'll wait here, don't make me feel too alone!

### Re: Anybody wants to talk PHYSICS?

#2
Sure.

Is it possible for a singularity to have sufficient mass for energy binding to completely negate the gravitational field?

Alternatively, is there a mathematical difference between energy binding, and using distance adjusting for curvature?

Is it possible for a singularity to have sufficient mass for energy binding to completely negate the gravitational field?

Alternatively, is there a mathematical difference between energy binding, and using distance adjusting for curvature?

### Re: Anybody wants to talk PHYSICS?

#3
Here's one you might enjoy.

Derive the Schwarzschild radius of a black hole.

Derive the Schwarzschild radius of a black hole.

### Re: Anybody wants to talk PHYSICS?

#4
Tough ones. I would need a solid base in general relativity and quantum mechanics to answer those questions, which I lack at the moment.

I will come back to you next semester, armed with that knowledge

I will come back to you next semester, armed with that knowledge

### Re: Anybody wants to talk PHYSICS?

#5
Tension on a pulley string will be different at both ends if the pulley has a large enough moment of inertia.

### Re: Anybody wants to talk PHYSICS?

#6Tenori Wrote: Tension on a pulley string will be different at both ends if the pulley has a large enough moment of inertia.

It actually only needs a non-zero moment of inertia. In such a case, in order to achieve an angular acceleration of the pulley itself you need to have a torque. And you can’t have that if the tension at the two ends is the same.

### Re: Anybody wants to talk PHYSICS?

#7
Wasn't my intention to purposely pose a question that wasn't included in your curriculum. I just assumed relativity was part of Physics III.

Let's try something a bit more classical Physics related.

What two forces must be in equilibrium for an object to be in a stable circular orbit?

Let's try something a bit more classical Physics related.

What two forces must be in equilibrium for an object to be in a stable circular orbit?

### Re: Anybody wants to talk PHYSICS?

#8Don't worry, it's actually my university choice to split the two up. We did special relativity back with physics 1, then I skipped physics 2 because I'm a moron, and physics 3 is basically the failure of classical physics and the birth of quantum mechanics.

Next semester I'll have a look at both general relativity and quantum mechanics much more in depth, with dedicated exams and all.

As for your question... Why do I feel like there's a trap hidden somewhere? My quick answer would be that the centripetal acceleration must be provided by the gravitational force. Therefore using Newtonian mechanics we have

So, basically adding an image to this forum via iPad is a lost cause. I tried to boot up my PC and... you guess it? Chrome froze and hung up on me like my ex when she dumped me back in the day. In the end, after several minutes, I was finally able to upload this bad handwriting. Enjoy!

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### Re: Anybody wants to talk PHYSICS?

#9
Quite correct and a bonus for including the derivation of the orbital velocity. Only one slight nitpick. It's centrifugal force which acts against gravity. As you correctly pointed out, centripetal force is what causes an object to move in a circular path which in the case of a circular orbit is gravity. Centrifugal force is due to the inertia of an object in orbit causing it to want to move in a straight line.

### Re: Anybody wants to talk PHYSICS?

#10You're right! I got sidetracked with the calculations and forgot the original question altogether!

### Re: Anybody wants to talk PHYSICS?

#11Luca Wrote: I do love to reply to idiotically complex questions

How about an idiotically complex Hard Science Fiction story? I have a tale called The Life Factor, where a kid and his brother discover the Eleven Dimensions of M Theory, and use them to travel through time. I have so many notes for story, it's absurd, including a glossary of terms and inventions -- half of them real and half of them not.

It starts out with Ed and Johnny Power getting their hands on a Portable Fusion Reactor, and using it to clear out all the Higgs Bosons in Grandpa's harness shed. It's too unwieldy to do the job, so they replace it with a few billion Subatomic Particle Engines, which all pretty much fit in a breadbox. Then, by wiring a fMRI skullcap to their machine, whenever it decoheres (due to the lack of Higgs Bosons) a person can 'think' their way to a different place in Spacetime, where they recohere.

Pretty cool, huh? Can you guess which part I made up? 🤔

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### Re: Anybody wants to talk PHYSICS?

#12
Hi, so you're into physics, huh? Well, coincidentally, I am currently working on a story that has heavy elements of physics in it, particularly quantum locking and superconductors. It's called "Sleight of Nano". Check it out if you want:

https://www.royalroad.com/fiction/37002/sleight-of-nano

By the way, a couple of questions regarding quantum locking and superconductors. Let's say that it is possible for room-temperature superconductors to exist, does that mean we could potentially be able to lift heavy objects made of that material with our minds like some sort of "quantum telekinesis"?

https://www.royalroad.com/fiction/37002/sleight-of-nano

By the way, a couple of questions regarding quantum locking and superconductors. Let's say that it is possible for room-temperature superconductors to exist, does that mean we could potentially be able to lift heavy objects made of that material with our minds like some sort of "quantum telekinesis"?