Lee and Leigh are twins. At their first birthday party, Lee is placed on a spaceship that travels away from the earth and back at a steady 0.714 c . The spaceship eventually returns, landing in the swimming pool at Leigh's eleventh birthday party. When Lee emerges from the ship, how old is he? a. He is still only 1 year old
b. He is 8 years old
c. He is also 11 years old
d. He is 18 years old

b. He is 8 years old

Explanation:

We will use Einstein's formula for time dilation, to calculate the age of Lee. Because Lee was traveling comparable to the speed of light, his age must be lesser than Leigh.

where,

T₀ = Time on Earth = ?

T = Relative Time = 10 years

v = relativistic speed of Lee = 0.714 c

c = speed of light = 3 x 10⁸ m/s

Therefore,

T₀ = 7 years

Hence, the age of Lee will be:

b. He is 8 years old

answer; how far out of place which the object finished relative to the starting location;