A person travels on a spaceship moving at a speed of `5c / 13`. (a) Find the time interval calculated by him between the consecutive birthday celebrations of his friend on the earth . (b) Find the time interval calculated by the friend on the earth between the consecutive birthday celebrations of the traveller.

Explanation

(a) Here ` u = 5c/ 13 `
`Delta t = t / (sqrt 1 -u^(2) / c^(2))
` = 1 y / (sqrt 1 - 25c^(2) / 169c^(2)) `
` =y xx 13/ 12 = 13 / 12 y `
The time inteval between the consecutiove birthday celebration is 13 / 12 y .
(b) The friend on the earth also calculates the same speed.