One 20-year-old twin brother takes a space trip with a speed of ...

[Deast7027]

One 20-year-old twin brother takes a space trip with a speed of 0.80c for 30 years according to a clock on the spaceship. Upon returning to the Earth, what is his own age and the age of the Earth-based twin brother?
 
  A) 20; 30
  B) 30; 50
  C) 40; 60
  D) 50; 70
  E) 70; 90

Question 2

An ideal polarizer is placed in a beam of unpolarized light and the intensity of the transmitted light is 1.000. A second ideal polarizer is placed in the beam with its referred direction rotated 40 to that of the first polarizer.
 
  What is the intensity of the beam after it has passed through both polarizers? A) 0.7661
  B) 0.4131
  C) 0.5868
  D) 0.6431
  E) 0.5000

[Meganchabluk]

Answer to Question 1

D

Answer to Question 2

C