Go Back   Physics Help Forum > College/University Physics Help > Special and General Relativity

Special and General Relativity Special and General Relativity Physics Help Forum

Like Tree1Likes
  • 1 Post By kiwiheretic
Reply
 
LinkBack Thread Tools Display Modes
Old Jul 6th 2017, 10:04 AM   #1
Member
 
Join Date: Feb 2017
Posts: 38
Example of length contraction and time dilation.

Is my interpretation correct?

When you travel at 0.999 speed of light then to you what 3 seconds has passed is actually 67.2 seconds to an observer on earth if you are in a spaceship that is traveling fast.

Also 1 meter to you on the spaceship would be observed as 0.45 meters on earth. This way time dilation works and length contraction also.

Also note time is time into gamma and length is length/gamma. Also gamma @ 0.999 speed of light is 22.4.

Is this correct?
avito009 is offline   Reply With Quote
Old Jul 6th 2017, 12:42 PM   #2
Senior Member
 
Join Date: Nov 2013
Location: New Zealand
Posts: 401
$\displaystyle \gamma = \frac{1}{\sqrt{1 - \frac{v^{2}}{c^{2}}}}$

When you travel at 0.999 speed of light then to you what 3 seconds has passed is actually 67.2 seconds to an observer on earth if you are in a spaceship that is traveling fast.
Close. I think its 67.1

Also 1 meter to you on the spaceship would be observed as 0.45 meters on earth. This way time dilation works and length contraction also.
No, I think the contraction is observed by you on the spaceship, not by the person on the earth.

Gamma is "cooked up" so that all observers see the speed of light as the same. So one observer will measure light travelling across a distance x in time t as c = x/t and another observer travelling at velocity v will see light travelling across a distance x/gamma and taking time t/gamma so to keep the speed of light the same we would need to calculate the length contraction of 1 meter as 1/gamma(0.999).

Time dilation is a bit confusing because it refers to the time you would see viewing a clock on earth with a very good telescope from your spaceship. It's not the time you measure directly like length contraction. That's why we divide by gamma for both x and t to change distance and time on earth to results we would see from spaceship.
kavinmathi likes this.
kiwiheretic is offline   Reply With Quote
Old Jul 6th 2017, 10:34 PM   #3
Junior Member
 
Join Date: Jul 2017
Location: China
Posts: 2
@avito009:I think you are right 1
linxf is offline   Reply With Quote
Old Jul 6th 2017, 10:36 PM   #4
Junior Member
 
Join Date: Jul 2017
Location: China
Posts: 2
@avito009:sorry, the time dilation that you caculated is right,but the length conctraction is 0.045m .

Last edited by linxf; Jul 6th 2017 at 11:03 PM.
linxf is offline   Reply With Quote
Old Jul 6th 2017, 10:38 PM   #5
Senior Member
 
Join Date: Nov 2013
Location: New Zealand
Posts: 401
I got a different result for the length contraction and explained in my last post why. Perhaps I wasn't clear on that.
kiwiheretic is offline   Reply With Quote
Reply

  Physics Help Forum > College/University Physics Help > Special and General Relativity

Tags
contraction, dilation, length, time



Thread Tools
Display Modes


Similar Physics Forum Discussions
Thread Thread Starter Forum Replies Last Post
regarding the length contraction and time dilation in special theory of relativity vikas katoch Special and General Relativity 3 Oct 8th 2016 07:00 AM
Question about length contraction fredreload Special and General Relativity 5 Dec 8th 2015 08:44 AM
Length Contraction problem savior_self Special and General Relativity 0 Nov 8th 2011 12:34 PM
Length contraction werehk Special and General Relativity 4 May 15th 2009 02:11 PM
Length Contraction kkh814 Special and General Relativity 1 Feb 28th 2009 08:03 AM


Facebook Twitter Google+ RSS Feed