- #1
ducmod
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Homework Statement
Hello!
This is an elementary problem, but I somehow can't compute it.
How long does it take light to travel in:
(a) 1.0 ft (report answer in nanoseconds)
(b) 4.5 billion km, the average separation between
the sun and Neptune (report answer in hours
and minutes)
Here is what I have tried:
(a) I assume 1.0ft means 1 foot. Light travels 3 x 10^8 meters / second, or 186 000 miles per second (information from a chemistry textbook). 1 meter = 3.2808 feet, hence
9.8424 x 10^8 feet in 1 second
1 foot in x seconds
hence it takes 1 / (9.8424 x 10^8) = 0.10168 x 10^(-8) seconds
To transfer to nanoseconds, I need to divide by 10^(-9), and I get 0.10168 x 10^(-8) / 10^(-9), hence
I get 1 nanosecond as the answer. Correct?
(b) 3 x 10^8 meters / second, hence 0.003 x 10^8 km/ second,
4.5 x 10^8 km / 0.003 x 10^8 km = 1500 seconds
There are 3600 seconds in one hour, hence 3600 / 1500 = 2.4 hours.
This answer is wrong, it should be 4 hours 10 minutes
Thank you!