LVAAS - THE LEHIGH VALLEY AMATEUR ASTRONOMICAL SOCIETY: Promoting, Facilitating and Teaching Astronomy Since 1957
Login

Welcome to LVAAS, Anonymous
Tuesday, May 23 2017 @ 06:56 AM EDT


 Forum Index > Activities & General Discussion > All Astronomy and Cosmology Topics
 Show me the math!
 |  Printable Version
By: Anonymous: maroth () on Friday, December 16 2005 @ 01:39 PM EST (Read 16102 times)  
Anonymous: maroth

Question is open to anyone with some facility with math.................

How long would it take a spaceship to accelerate from zero to the speed of light at a rate that would make the occupants feel a continuous 2 G's ?

MR





       
   
By: Anonymous: MikeEddinger () on Friday, December 16 2005 @ 02:14 PM EST  
Anonymous: MikeEddinger

Well, 1G is 32 ft/sec per second or 32 ft/sec^2. This means 2G's would be 64 ft/sec^2. So after one second, you'd be going 64 ft/s, and after two seconds you'd be going 128 ft/s, etc.

The speed of light is 186,000 mile/sec (everything in this analysis is rounded slightly.... it does not make a substantial diff). Therefore, the speed of light is

c = 982,080,000 ft/s

So, if we accelerate at 64 ft/sec^2 we find

time to light speed = 982,080,000(ft/s) / 64 (ft/sec^2)

time to light speed = 15,345,000 seconds

time to light speed = 177 days, almost exactly 1/2 year

Of course Einstein says you can't go the speed of light... a side effect of special relativity... as you approach the speed of light, mass increases, and therefore the amount of energy needed to provide the "force" to continue to accelerate you at 64 ft/sec^2 goes to infinity (f=ma). Maybe you could go to 95% the speed of light, but at that point, time is not an issue anymore, as your spaceship clock is running at about 1/3 the speed of the clock on earth.... you could travel for 20 years and return to find ever adult who was alive when you left is dead... so... what would be the point (unless you have in-laws) !!





       
   
By: Anonymous: maroth () on Friday, December 16 2005 @ 03:48 PM EST  
Anonymous: maroth

That is what my brother LAR came up with.

Who would make the best interstellar travellers?

Monks!!!!!!!!! They hardly need or even WANT anything.

MR



i am searching for a nerve in this society..................





       
   
By: Anonymous: MikeEddinger () on Friday, December 16 2005 @ 04:52 PM EST  
Anonymous: MikeEddinger

Nerds too... they would be happy as long as the spacecraft had a lot of computers, and a network that would allow continuous games of Doom or Medal of Honor.





       
   
By: Anonymous: dmurphy () on Sunday, December 18 2005 @ 04:08 AM EST  
Anonymous: dmurphy

Quake anyone?

Twisted





       
   
By: Anonymous: MikeEddinger () on Sunday, December 18 2005 @ 01:32 PM EST  
Anonymous: MikeEddinger

Ya, maybe we could even MAKE OUR OWN quake level..... perhaps a pulpit rock quake map. Think we have anybody in the society who might be able to make us such a map?





       
   
By: Anonymous: WNKnisely () on Sunday, December 18 2005 @ 05:33 PM EST  
Anonymous: WNKnisely

[quote="MikeEddinger"]Of course Einstein says you can't go the speed of light... a side effect of special relativity... as you approach the speed of light, mass increases, and therefore the amount of energy needed to provide the "force" to continue to accelerate you at 64 ft/sec^2 goes to infinity (f=ma). Maybe you could go to 95% the speed of light, but at that point, time is not an issue anymore, as your spaceship clock is running at about 1/3 the speed of the clock on earth.... you could travel for 20 years and return to find ever adult who was alive when you left is dead... so... what would be the point (unless you have in-laws) !![/quote]

Since today seems to be one of the days my browser will let me log in (grin) I can respond. Mike has this right. The real calculation is pretty complicated.

As you approach lightspeed, your velocity increases in a non-linear manner so the use of simple kinematics is right out. And as Mike notes, as you get closer to lightspeed, your Energy increases enough that your kinetic energy becomes significant when compared to your mass energy - which has the effect of making it seem like your mass (mass field really) is increasing as you approach c. This means it takes more and more work to speed up a littler and littler amount.

The real calculation gets pretty hairy. You're not in the realm of special relativity and you have to use the full Riemannian structure of General relativity since you're accelerating the whole time. Yuck.

Here's more information if you're interested...
http://answers.google.com/answers/threadview?id=118993





       
   
By: Anonymous: KEddinger () on Sunday, December 18 2005 @ 10:01 PM EST  
Anonymous: KEddinger

[quote="MikeEddinger"]Ya, maybe we could even MAKE OUR OWN quake level..... perhaps a pulpit rock quake map. Think we have anybody in the society who might be able to make us such a map?[/quote]

I like to stick with the levels that take place in famous locations.





       
   
By: Anonymous: MikeEddinger () on Monday, December 19 2005 @ 11:28 AM EST  
Anonymous: MikeEddinger

Nick... any good sources to explain why time slows down for the traveler near the speed of light? I think it has to do with refernece frames, but this one has always perplexed me. How is it that my body would age more slowly because I am on a rocket traveling near the speed of light? How can I be gone 20 years, and my body only age 20 years, while people on earth aged 60? Getting down to the most fundamental level, why have my cellular processes (relative to the person on earth) slowed? I have never been able to get a grasp on this one. Being a Meyers-Briggs ENTP, I always need to find an intuitive hook... that's tough with relativity.





       
   
By: Anonymous: Donna () on Monday, December 19 2005 @ 08:42 PM EST  
Anonymous: Donna

Doesn't it have to do with distance being the same in all frames of reference? v = d/t so if v is increasing and distance is the same, time has to be getting smaller.





       
   



 All times are EDT. The time is now 06:56 AM.
Normal Topic Normal Topic
Locked Topic Locked Topic
Sticky Topic Sticky Topic
New Post New Post
Sticky Topic W/ New Post Sticky Topic W/ New Post
Locked Topic W/ New Post Locked Topic W/ New Post
View Anonymous Posts 
Able to Post 
Filtered HTML Allowed 
Censored Content 

My Account






Lost your password?

Redshift Store

Order LVAAS Merchandise Online


Current Moon Phase

CURRENT MOON

Topics

Older Stories

Friday 29-May