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Question
'The distance of a star from the earth is 8.33 light minutes.' what do you mean by this statement? Express the distance in metre.
Solution
'The distance of a star from the earth is 8.33 light minutes' implies, it takes 8.33 minutes for light to reach the earth from the star.
As we know,
Distance = speed × time
Given,
Speed = 3 × 108ms-1
Time = 8.33 min
= 8.33 × 60s
= 499.8s
≈ 500s
Substituting the values in the formula above we get,
Distance = 3 × 108 × 500
= 1500 × 108
= 1.5 × 1011
Therefore, the distance from the star to the earth is 1.5 × 1011 m.
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