Question

An astronaut is out in space with an extremely precise timing device measuring the speed of various fast‑moving objects. A laser gun is mounted on a spaceship and aimed backward. As the spaceship flies away from the astronaut at a speed of 200 million m/s, the laser shines a beam of light toward him. Determine the speed that would be measured in each of the cases listed. The speed of the laser light as measured in the astronaut's reference frame. The speed of the laser light measured in the spaceship's reference frame. The speed of the laser gun as measured in the astronaut's reference frame. The speed of the laser gun measured in the spaceship's reference frame.

Answer 1

Answer and Explanation:

with reference to Einstein's theory of special relativity, the speed of an electromagnetic radiation, here, laser will not change in any inertial frame or remains same irrespective of any change in inertial frame.

Therefore, the speed of light measured in both the cases, i.e., in astronaut's reference frame and spaceship's reference frame will be equal to the speed of light in vacuum, i.e., $3\times 10^{8} m/s$.

The laser gun's speed in astronaut's reference frame is the same as the speed of the spaceship as it mounted on it, i.e., the speed of the laser gun is 200 million m/s.

The laser gun's speed measured in spaceship's reference frame will be zero, as it is mounted on the spaceship and is stationary in the spaceship's reference frame.