Q91 of 111 Page 337

A light year is the distance that light can travel in one year.

1 light year = 9,460,000,000,000 km.


(a) Express one light year in scientific notation.


(b) The average distance between Earth and Sun is 1.496 × 108 km. Is the distance between Earth and the Sun greater than, less than or equal to one light year?


(a) For the standard form notation, only one number is kept before the decimal point and rest all numbers are written after decimal point.

The power of 10 denotes the number of terms shifted after the decimal point.


So for 9,460,000,000,000


Here only one number will be kept before decimal point that is 9.


Number of terms to be shifted after decimal point = 12



9,460,000,000,000 = 9.46 × 1012 km


(b) One light year = 9.46 × 1012 km


Distance between Sun and Earth = 1.496 × 108 km


It is clearly seen that one light year is greater than the distance between sun and earth.


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