🔋college physics i – introduction review

Length contraction

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

Length contraction is the phenomenon where the length of an object moving at relativistic speeds appears shorter along the direction of motion when observed from a stationary frame of reference. This effect is a direct consequence of Einstein's theory of special relativity.

5 Must Know Facts For Your Next Test

  1. Length contraction only occurs in the direction parallel to the object's motion.
  2. The formula for length contraction is $L = L_0 \sqrt{1 - \frac{v^2}{c^2}}$, where $L$ is the contracted length, $L_0$ is the proper length, $v$ is the velocity of the object, and $c$ is the speed of light.
  3. At speeds much less than the speed of light, length contraction effects are negligible.
  4. Length contraction becomes significant as an object's speed approaches the speed of light.
  5. Observers moving with the object do not perceive any length contraction; it only occurs relative to stationary observers.

Review Questions

"Length contraction" also found in: