Question

A new unit of length is chosen such that the speed of light in vacuum is unity. The distance between the Sun and the Earth in terms of the new unit, if light takes 8 minute and 20 sec to cover the distance is ………

(a) 100 new unit 

(b) 300 new unit 

(c) 500 new unit 

(d) 700 new unit

Answer 1

(c) 500 new unit

Speed is unity = 1 unit/sec

 Time = 8 min and 20 sec = 500 sec 

Distance b/w sun and earth = Speed × Time 

= 1 × 500 = 500 unit