The best answer to any question.

April 17 2015 7:12 AM

How Large Would the Interstellar Spacecraft Need to Be for Simulated Gravity to Work?


Answer by Robert Frost, NASA engineer with specialization in spacecraft operations; orbital mechanics; and guidance, navigation, and control systems:



The idea of simulated gravity comes from substitution of the reaction force to centripetal force in place of the force of gravity. To provide this simulated gravity, thespacecraft would be rotated, causing the inner contents to be pushed against the outer edge, giving a sensation of weight. The formula for this force is: F = mω2r = mg.


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April 16 2015 7:34 AM

What Do Marines Do Between Deployments?

Answer by Jon Davis, sergeant of Marines, fought in Iraq during Operation Iraqi Freedom, amateur military historian:

This answer is Marine Corps–specific. Different units have different rotation cycles. My group (a military unit of similar size to a regiment) consisted of four squadrons that rotated in seven-month cycles. That meant that we had about seven months in country, then a year back at home, and the rest of the time was spent in extensive training to get ready to head back. Each squadron was at a different phase of the cycle than the others, always rotating perpetually until the war was over.

April 15 2015 12:24 PM

What’s the Difference Between Apple Watch Models?


Answer by Mills Baker, product strategy and design at Mokriya:



Deciding which Apple Watch model to buy should run a bit like this:



  1. Are any of the watch cases aesthetically superior in your reckoning to any others? Are any practically superior?
  2. How soon will you be replacing this watch? For how long a period of time will you benefit from the improved aesthetics of your preferred case?



So, first: Are any of the cases superior to the others? It's a rare buyer who wants to spend enough to get a gold case for the first version of this product line, in my estimation. For most of us, the choice is between the aluminum sport case and the stainless steel Apple Watch case.


April 14 2015 7:43 AM

Why Does Anyone Want to Be a Doctor?

Answer by James Pan, med student at Stanford:

The alternatives to medicine are much easier if your primary goal is to make money. To become a doctor, and especially a specialist who earns in the top quartile of physicians, you'll need four years undergrad, four years med school, and then five-plus years of residency and fellowship training. That represents around half a million dollars in tuition and living costs on top of associated opportunity cost. You're also giving up most of your 20s and part of your early 30s in pursuit of miserable 80-plus hour workweeks.

April 13 2015 2:13 PM

How Do You Improve Self-Expression Skills?

Answer by John Ramos, owner of the Student Power:

It's all about getting the message across, isn't it? In the last few months, I think I've improved my communication skills considerably. Here's what I did:

Write (almost) everyday. I committed to writing 500-1,000 words a day, whether on Quora, my blog, or my book. It forces you to find the right words and expressions to convey your message. You'll start to notice that some sentences are poorly built. Verbose and clutter become a constant concern. You start turning fragile suggestions into powerful affirmations.

April 10 2015 7:40 AM

What Was Dental Hygiene Like During the Middle Ages?

Answer by Tim O'Neill, M.A. in medieval literature and have studied most aspects of the period for many years:

People in the Middle Ages considered healthy, white teeth a sign of beauty and wrote of sweet-smelling breath as a desirable attribute. So, not surprisingly, we have extensive evidence that people liked to keep their teeth clean and a large amount of evidence of toothpastes and teeth powders, as well as mouth washes and treatments for halitosis.

April 9 2015 7:42 AM

How Do Some People Always Stay Upbeat?

Answer by Franklin Veaux, small-business owner, sexuality educator, writer:

I am a person who is upbeat almost all the time.

Nobody is always upbeat, of course. Everyone is capable of pain and sorrow, hurt and heartbreak. But I'm resilient. Sadness doesn't stick to me. On the rare occasions when I feel unhappy, that unhappiness is transient. My normal emotional state is deeply, profoundly happy. If you could bottle how I feel most of the time and sell it, there might never be another war again.

April 8 2015 7:22 AM

Do Astronauts Aboard the International Space Station Have Cleaning Schedules?

Answer by Clayton C. Andersonauthor, U.S. astronaut, retired:

If I answer this question, please don't tell my wife! You see, on board the International Space Station, we were scheduled to "clean" our home every Saturday morning. Since I was the only U.S. astronaut living on ISS at that time (June to November 2007), I was responsible for cleaning the entire U.S. segment. If she finds out I actually do cleaning, it could spell doom for me here in Houston.

April 5 2015 7:17 AM

Why Isn’t Jazz More Popular?

Answer by Mills Baker, studied and played music:

Many of these answers are excellent; I think they largely suffice to explain why jazz isn't more popular. But I think one controversial dynamic has gone unmentioned: race. Because this question is not really about the absolute popularity of jazz—after all, why isn't classical music more popular? or polka?—but about its decliningpopularity.

April 3 2015 1:09 PM

What’s the Hardest Part of Being a Twin?

Answer by Kah Seng Tay, an identical twin:

I'm an identical twin of many years, with my other twin—ahem—within close proximity (through school, home, and work) for all but three years of that.

I have a list of these difficulties: