Jack and Jill are fiercely competitive siblings, and since they ...

[cdr_15]

Jack and Jill are fiercely competitive siblings, and since they were born exactly a year apart, can compete in most everything. Jill, the younger, always resented her older brother for being just that: older. When they got older, Jack resented Jill's youthful advantage of one year. Imagine that Jack builds himself a high- tech spaceship and races off into space, knowing that he can at least slow down his aging. If he were gone for one year according to Jill, which of the following statements could be or are true?
  II, IV
  I, III, IV
  I, IV
  I, III, V
  II, V

Question 2

Which of the following descriptions shows two objects of EQUAL mass-energy?
 

Two identical balls with the same speed and at the same height, except moving vertically in different directions
  A 10 kg sphere of iron at 300 K and a 12 kg sphere of iron at 10 K
  Two identical spheres of copper, except one is at 300 K and one is at 3000 K
  Two identical bullets, except one bullet is fired from a special gun at 0.5c and the other bullet is at rest.

[kishoreddi]

Answer to Question 1

I, III, V
All three of these statements are true. Jack is older. Each believes that the other's clock is ticking slower during the one-way outbound trip.

Answer to Question 2

The objects have the same rest mass, are moving with the same speed, and have the same amount of potential energy. The direction of travel does not affect the mass-energy.

[cdr_15]

Gracias!

[kjohnson]

Great answer, keep it coming