Question

The distance of the Sun from the earth is one hundred forty million four hundred thousand kilometers and light travels from the former to the latter in $7$ minutes and fifty eight seconds. The velocity of light per second is:

• A. $3\times {10}^5$ km/sec
• B. $0.3\times {10}^5$ km/sec
• C. $30\times {10}^5$ km/sec
• D. None of these

Answer 1

Answer: (A)

$3\times {10}^5$ km/sec

Distance covered is $140,400,000km=140.4\times {10}^6$km

Time taken is $478$ sec

So, the speed is $\frac{140.4\times {10}^6}{478}=2.937\times {10}^{5}km/sec$

which is approx $3\times {10}^{5}km/sec$.