<img src="https://d5nxst8fruw4z.cloudfront.net/atrk.gif?account=iA1Pi1a8Dy00ym" style="display:none" height="1" width="1" alt="" />
Dismiss
Skip Navigation

Length Contraction

As the velocity of an object approaches the speed of light it appears to change length to a stationary observer.

Atoms Practice
Estimated4 minsto complete
%
Progress
Practice Length Contraction
 
 
 
MEMORY METER
This indicates how strong in your memory this concept is
Practice
Progress
Estimated4 minsto complete
%
Practice Now
Turn In
Length Contraction

Clocks moving towards or away from you run more slowly, and objects moving towards or away from you shrink in length. These are known as Lorentz time dilation and length contraction; both are real, measured properties of the universe we live in.

An object moving with speed has a dimensionless speed calculated by dividing the speed by the speed of light (). .

The dimensionless Lorentz “gamma” factor can be calculated from the speed, and tells you how much time dilation or length contraction there is. .

If you see an object of length moving towards you at a Lorentz gamma factor , it will appear shortened (contracted) in the direction of motion to new length .

Object Speed (km/sec) Lorentz Factor
Commercial Airplane
Space Shuttle
UFO ☺
Electron at the Stanford Linear Accelerator

 

Review

  1. What would be the Lorentz gamma factor for a space ship traveling at the speed of light c? If you were in this space ship, how wide would the universe look to you?
  2. How fast would you have to drive in your car in order to make the road % shorter through Lorentz contraction?
  3. In 1987 light reached our telescopes from a supernova that occurred in a near-by galaxy light years away. A huge burst of neutrinos preceded the light emission and reached Earth almost two hours ahead of the light. It was calculated that the neutrinos in that journey lost only minutes of their lead time over the light.
    1. What was the ratio of the speed of the neutrinos to that of light?
    2. Calculate how much space was Lorentz-contracted form the point of view of the neutrino.
    3. Suppose you could travel in a spaceship at that speed to that galaxy and back. It that were to occur the Earth would be years older. How much would you have aged?

Review (Answers)

  1. , the universe would be a dot

Notes/Highlights Having trouble? Report an issue.

Color Highlighted Text Notes
Please to create your own Highlights / Notes
Show More

Image Attributions

Explore More

Sign in to explore more, including practice questions and solutions for Length Contraction.
Please wait...
Please wait...