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Matter In Our Surroundings

Question
CBSEENSC9005703

Light travels with a speed of 3 × 108 m/s. How long does the light take to reach earth from the sun which is 1.5 × 1011 m away?

Solution
Speed space of space light comma space straight v space equals space 3 space cross times space 10 to the power of 8 space straight m divided by straight s
Distance space between space Earth space and space Sun comma space straight s space equals space 1.5 space cross times space 10 to the power of 11 straight m
Therefore, time taken to reach Earth from sun is, 
space space space space straight t space equals space straight s over straight v space
space space space space space space equals fraction numerator 1.5 space cross times space 10 to the power of 11 over denominator 3 space cross times space 10 to the power of 8 end fraction space

space space space space space space equals space 500 space straight s space

space space space space space space equals space 8 space min space 20 space straight s.