A new unit of length is chosen such that speed of light in vacuum is unity. distance between Sun and

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1.Units, Dimensions and Measurement

easy

A new unit of length is chosen such that the speed of light in vacuum is unity. What is the distance between the Sun and the Earth in terms of the new unit if light takes $8\; min$ and $20\; s$ to cover this distance?

A$480$

B$500$

C$720$

D$250$

Solution

Distance between the Sun and the Earth:
$=$ Speed of light $\times$ Time taken by light to cover the distance
Given that in the new unit, speed of light $=1$ unit
Time taken, $t=8 \,min 20 \,s =500\, s$
$\therefore$ Distance between the Sun and the Earth $=1 \times 500=500$ units

Standard 11

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hard

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