Question

A light-year is the distance that light travels in one year. The speed of light is 3.00 × 108 m/s. How many miles are there in one light-year? (1 mi = 1609 m, 1 y = 365 d)
a 5.88 × 1012 mi
b 9.46 × 1015 mi
c 5.88 × 1015 mi
d 9.46 × 1012 mi

Answer 1

Answer:

(a) $5.88\times 10^{12}mi$

Explanation:

We have given speed of light $c=3\times 10^8m/sec$

Given time = 1 year =365 days

We know that in 1 minute = 60 sec

1 hour = 60×60 = 3600 sec

In one day = 24 hour = 24×60×60=86400 sec

So in 365 days = 365×86400$=3.1536\times 10^7sec$

We know that distance = speed ×time$=3.1536\times 10^7\times 3\times 10^8=9.46\times 10^{15}m$

We have given that 1 mi = 1609 m

So $9.46\times 10^{15}m=\frac{9.46\times 10^{15}}{1609}=5.88\times 10^{12}mi$So option (a) is correct