Question

A. The distance to a star is approximately 8.58 ✕ 10^18 m. If this star were to burn out today, in how many years would we see it disappear?

b. How long does it take sunlight to reach Earth?
c. How long does it take for a microwave radar signal to travel from Earth to the Moon and back?

Answer 1

906.27931 years

8.34 minutes

2.56266 seconds

Step-by-step explanation:

v = Velocity of light =
`3* 10^8\ m/s`

s = Distance

Time is given by

`t=(s)/(v)\\\Rightarrow t=(8.58* 10^(18))/(3* 10^8* 365.25* 24* 3600)\\\Rightarrow t=906.27931\ years`

We would see the star disappear after 906.27931 years after it actually disappeared.

Distance between Earth and Sun = 150.18 billion m

`t=(150.18* 10^9)/(3* 10^8* 60)\\\Rightarrow t=8.34\ minutes`

It takes 8.34 minutes for sunlight to reach Earth.

Distance between Earth and Moon = 384.4 million m

`t=(2* 384.4* 10^6)/(3* 10^8)\\\Rightarrow t=2.56266\ s`

It takes 2.56266 seconds for a microwave radar signal to travel from Earth to the Moon and back.