Fred and Joanne both measure the length of a particular spaceship to be 100 m when it is on Earth.Joanne then gets into the spaceship and,after visiting the Moon,hurtles past Earth at a speed close to the speed of light.Fred,still on Earth,measures the length of the moving spaceship to be about 90 m.At the same time,Joanne (using her own meterstick)measures the length of the spaceship to be:

Question

Quizplus · Accepted Answer

According to the theory of relativity, as an object's speed approaches the speed of light, its length appears to shrink from the point of view of a stationary observer. This effect is known as length contraction. Therefore, Fred observes the spaceship to be shorter than it actually is due to Joanne's high speed. However, from Joanne's point of view on the spaceship, she is at rest and the spaceship appears to be its original length of 100 m. Therefore, the correct answer is B, Joanne measures the length of the spaceship to be 100 m because she is "at rest" on the spaceship.

Fred and Joanne Both Measure the Length of a Particular