Question

The distance from Earth to the star Epsilon Eridani is about 10.5 light years. Which of the following statements is true?
A. It would take a modern space vehicle 21.0 years to reach Epsilon Eridani.
B. It takes a ray of light 10.5 years to travel from Earth to Epsilon Eridani.
C. It would take a modern space vehicle 10.5 years to reach Epsilon Eridani.
D. It takes a ray of light 21.0 years to travel from Epsilon Eridani to Earth.

Answer 1

The correct answer is B. - It would take a ray of light 10.5 light years to travel from Earth to Epsilon Eridani, or vice-versa. Using our current technology it would take far longer than 21.0 years for a space ship from Earth to travel that far - I would have to guess many hundreds of years.

Answer 2

Answer:

B. It takes a ray of light 10.5 years to travel from Earth to Epsilon Eridani.

Explanation:

Light year is the unit of the distance between two points. It is defined as the distance traveled by light from one point to other for given interval of time.

So here if the distance is given as 10.5 light years then it means the distance between Earth and the given star is same as that the distance traveled by the light in 10.5 years.

So here we can say that distance is

$d = 3\times 10^8 (10.5 \times 365\times 24 \times 3600)$

$d = 9.93 \times 10^{16} m$

so here the correct answer will be

B. It takes a ray of light 10.5 years to travel from Earth to Epsilon Eridani.