Physics Unit26: Special Theory of Relativity (id: f18c99b3d)

[单选题]
A set of twins, Andrea andd kxs-9xda0 2i Courtney, are inrr,b7yg cqlgymv+;9 :itially 10 years old. While Courtney remains on Earth, Andrea rides on a space ship which travels away from Earth at a speed of 0.6c for five years (as measured by Courtney), the;rl+7c , yvb9qy:ggrmn turns around and comes back at 0.6c. When Andrea returns, Courtney is 20 years old. How old is Andrea upon her return?

A. $10 \; years$
B. $12 \; years$
C. $18 \; years$
D. $20 \; years$


参考答案:  C


本题详细解析: 暂无