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

(a)
`5.88* 10^(12)mi`

Step-by-step explanation:

We have given speed of light
`c=3* 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* 10^7sec`

We know that distance = speed ×time
`=3.1536* 10^7* 3* 10^8=9.46* 10^(15)m`

We have given that 1 mi = 1609 m

So
`9.46* 10^(15)m=(9.46* 10^(15))/(1609)=5.88* 10^(12)mi`So option (a) is correct