Question

7. The distance of a star from the earth is 8.33 light minutes. What do you mean by the statement? Express the distance in metre.


Class 9 ICSE
Ch - Measurements and Experimentation.

Answer 1

Hey there!

The statement 'The distance of a star from the earth is 8.33 light minutes' means that the light from the star takes 8.33 minutes to reach earth.

Given,

Speed of light = 3 * 10^8 m/s

Distance covered in 1 sec = 3 * 10^8

Time taken = 8.33 min = 8.33 * 60 s

Distance = speed * time = 3 * 10^8 * 8.33 * 60 = 1.5 * 10^11 m

Hope It Helps You!

Answer 2

The distance of a star from earth is 8.33 light minutes.

This means that it takes 8.33 minutes for light from the sun to reach earth.
FINDING DISTANCE FROM THE ABOVE STATEMENT:

We know speed of light =3×10^8
Time taken=8.33min

Speed=distance/time
Distance=speed×time
=3×10^8 m/s × (8.33×60) sec {8.33×60 because we are converting minutes to secounds,since speed of light is in m/s}
=1500×10^8 metres
=1.5×10^8 kilometre
Large distance like these are measured in light year or light minutes.
Light year:distance covered by light in 1 year.
Light minute: distance covered by light in 1 minute.