Question

You are traveling in a spaceship at a speed of 0.70c away from Earth. You send a laser beam toward the Earth traveling at velocity c relative to you.
What do observers on the Earth measure for the speed of the laser beam?

Answer 1

The question is asking to describe and state and calculate what do the observer on the earth measure for the speed of the laser beam, and base on my research, the answer would be v = 1bc, I hope you are satisfied with my answer and feel free to ask for more 

Answer 2

The speed of the light for the observers on the Earth appears to be $\boxed{c}$ moving towards the Earth.

Further Explanation:

The speed of the laser beam coming from the spaceship moving away from the Earth at the speed comparable to the speed of light is given by the Einstein’s theory of relativity.

According to the Einstein’s theory, the relative speed observed from the Earth is given as:

$u=\dfrac{{{v_{{\text{rel}}}}}}{{1 + \dfrac{{{v_{ship}}\cdot {v_{beam}}}}{{{c^2}}}}}$                  ......(1)

Here, $u$ is the speed of light for the observer on the Earth, ${v_{{\text{rel}}}}$ is the relative speed of the light observed from the spaceship,  ${v_{ship}}$  is the speed of the spaceship, ${v_{beam}}$ is the speed of the laser beam and $c$ is the speed of the light.

The relative speed of the light as observed from the spaceship moving away from Earth is:

${v_{{\text{rel}}}} = {v_{ship}} + {v_{beam}}$

Substitute the values of ${v_{ship}}$ and ${v_{beam}}$ in above expression.

$\begin{aligned}{v_{{\text{rel}}}} &= 0.7c + \left({ - c}\right)\\&= - 0.3c\\\end{aligned}$

Now, substitute the value of ${v_{{\text{rel}}}}$ in equation (1).

$\begin{aligned}u&=\dfrac{{ - 0.3c}}{{1 + \dfrac{{0.7c \times\left({ - c}\right)}}{{{c^2}}}}}\\&=\dfrac{{ - 0.3c}}{{1 - 0.7}}\\&= - c\\\end{aligned}$

The negative sign shows that the beam is moving opposite to the direction of motion of the spaceship.

Thus, the speed of the light for the observers on the Earth appears to be $\boxed{c}$ moving towards the Earth.

Learn More:

1. What is the frequency of light for which the wavelength is 7.1 × 102 nm brainly.com/question/9559140

2. Calculate the frequency of the red light emitted by a neon sign with a wavelength of 690 nm brainly.com/question/4594267

3. Which of the following statements about electromagnetic radiation is truehttps://brainly.com/question/1619496

Answer Details:

Grade: High School

Subject: Physics

Chapter: Speed of light

Keywords:

Spaceship, speed of 0.7c, laser beam, towards the Earth, theory of relativity, relative speed, observer, moving away from Earth, Earth, speed of light.