Question

Can someone please help me with this dimensional analysis problem, I will give a medal for best answer. I have to set the problem up and show my work using conversion.

Light in a vacuum travels at as speed of 3.00x10^8 m/s. If pluto was 3.6 billion (3.6x10^9mi) from the sun, how many minutes would it take sunlight to reach Pluto?

Answer 1

I tried to start working it out like this: (sec I'll post)

Answer 2

I tried converting the given speed of light from meters per second, to meters per minute.

Answer 3

But then I'm not sure what to do after that, or even if I did that correctly.

Answer 4

^you are close to the answer

Answer 5

Just not sure what to do next, but I think I'm suppose to convert meters per minute to miles per minute . . . but then I don't know how the (3.6x10^9mi) works into the problem >_<

Answer 6

rather than converting to minutes initially, why not set up the problem to find the time in seconds? So you have 3*10^8 m/s for light and the distance being 3.6*10^9 mi. There is 1609 meters in a mile. So first you have 3.6*10^9*1609 = ? meters. Now solve for the time which would be the previous answer over the speed of light. You now know the time in seconds, and all you have to do is convert to minutes.

Answer 7

Oh okay, I can try that. Let me try working it out, just a min.

Answer 8

Sure thing. Essentially what it boils down to is that you are given two separate unit systems to deal with. Metric (m/s) and English (miles) you need to convert one to the other in order to work the problem. It's usually easiest and standard practice to convert the English units over into the metric system (E.g.: Miles into Kilometers or meters) Time is universal so you don't need to worry about seconds minutes or hours until the end and that's only if the question asks for a answer in seconds minutes hours etc. ... did that make sense?

Answer 9

I'm still trying to work out the problem, but that does make sense. I didn't realize it was easier to convert english to metric, so I guess I was kind of doing it backwards. Thank you for your help and advice.

Answer 10

I got the answer, it will take 320 minutes!

Answer 11

Thank you so much Rhystic! <3

Answer 12

it's not necessarily easier to convert from English to metric that was my fault in stating that. Its easier to work in metric though because everything is usually in tens from one unit to the next. Eg: 1000 meters = 1 kilometer while 5280 feet = 1 mile.

Answer 13

sure thing.

Answer 14

Ah okay, gotcha, well still thank you, just glad I finally understand how to work the problem out!