Question

Problem 3:A starship voyages to a distant planet 10 ly away. The astronauts in the starship reach theplanet and then they immediately return to the Earth at the same speed. The round trip from the Earthto the planet and back to the Earth takes 25 years.(a) What is the speed of the starship

Answer 1

Answer:

speed = 0.8c

Explanation:

Given :

Distance from earth to the distant planet = 10 ly

Time taken by the astronauts for the entire journey = 25 years

The time taken to reach the planet is $t_1=\frac{25}{2}$

                                                                  = 12.5 years

Therefore, speed of the starship can be calculated by :

$\text{Speed} = \frac{\text{distance}}{\text{time}}$

$v=\frac{10 \times c \times 3.15 \times 10^7}{12.5 \times 3.15 \times 10^7}$

  $=0.8c$

Therefore the speed of the starship is 0.8c