Read the following SAT test question and then click on a button to select your answer.

L=L0√(1-v^2/c^2)

An object's observed length depends on its speed relative to the observer. The observed length L is described by the above equation, where v is the speed of the object relative to the observer, c is the speed of light, and L subscript 0 is the observed length when the object is at rest relative to the observer. Which of the following correctly expresses the object's speed in terms of L, L0, and c?

v=√(c^2-L^2/L0^2)
v=√(1-c^2L^2/L0^2)
v=c(1-L^2/L0^2)
v=c√(1-L^2/L0^2)

來源:可可英語 http://www.ccdyzl.cn/sat/202002/605242.shtml