Question

Bob is moving at 0.967c with respect to Alice. At the exact instant he passes Alice, she fires a very short laser pulse in the same direction Bob is moving. (a) After 5.59 s has elapsed on Alice's watch, what distance does Alice measure between Bolb and the laser pulse? (b) After 5.59 s has elapsed on Bob's watch, what distance does Bob measure betweern himself and the laser pulse?

Answer 1

Explanation:

Speed of Bob, v = 0.967 c

At the exact instant he passes Alice, she fires a very short laser pulse in the same direction Bob is moving.

(a) We need to find the distance measured by Alice  between Bob and the laser pulse. It is given by :

$d=ct-vt$

$d=t(c-v)$

$d=5.59\times (c-0.967c)$

$d=5.53\times 10^7\ meters$

(b) Distance measured by Bob between himself and the laser pulse is given by :

$d_B=ct$

$d_B=3\times 10^8\times 5.59$

$d_B=6.67\times 10^9\ meters$

Hence, this is the required solution.