One 20-year-old twin brother takes a space trip with a speed of 0.80c for 30 years according to a clock on his spaceship. At the end of this trip, what are (a) his own age and (b) the age of his
Earth-based twin brother?
A) (a) 50 y (b) 70 y
B) (a) 20 y (b) 30 y
C) (a) 70 y (b) 90 y
D) (a) 30 y (b) 50 y

Question

Quizplus · Accepted Answer

The traveling twin ages 30 years during the trip, making him 50 years old. Due to time dilation, the Earth-based twin ages more, reaching 70 years.

One 20-Year-Old Twin Brother Takes a Space Trip with a Speed