PA_M7_S2_T2_Converting
Units of Time Transcript
Time is one of the units that people tend to feel the most comfortable
with in terms of converting. Like all of our other particular
measurements we've talked about, we do have conversion units. Typically,
if I want to go from minutes to seconds, there are 60 seconds in every
minute. There are 60 minutes in each hour, 24 hours in each day, and 365
days in each year. 365 days a year is taken to be a standard conversion
and we tend to ignore leap year unless we're specifically looking at it.
Just like my other conversion processes, I want to set up my conversions
so that the units cancel appropriately, and the unit I'm left with is the
one I'm looking for. So here's an example, how many seconds are there in
a year?
Well, I don't have the direct year to seconds conversion, so I'm going to
simply say well, I have one year I want to go to seconds. The first thing
I'm going to do is find out how many days there are in a year. Well,
there 365 days in one year. This allows me to cancel the units of years.
Next, I know that each day is 24 hours. So there's 24 hours in one day,
that's going to allow me to cancel the day units. Next, I know that there
are 60 minutes in each hour, that's going to all ow me to cancel the hour
units, and finally I know that there are 60 seconds in each minute. Now
that I've got this setup it's just a matter of cancelling units and doing
the multiplications. Years cancel, days cancel, hours cancel, minutes
cancel, and I'm left with 365 * 24 * 60 * 60, and that's in seconds
because all my other units have canceled. I do that multiplication and I
get 31,536,000 seconds in a year.
Let's calculate the number of minutes in the 40 hour work week.
I have 40 hours in a
normal work week and there are 60 minutes per each hour. I simply have to
do the multiplication of 60 times 40 to get 2400 minutes, because my
hours cancel.
Let's change 345,600 seconds into days.
I
put my 345,600 seconds up here. I want to go to days, but I don't have a
direct conversion. I do happen to know that 1 minute is 60 seconds, that
allows me to cancel a seconds. I also know that 1 hour is 60 minutes,
which allows the council my minutes. I know that one day is 24 hours, so
that my seconds will cancel, my minutes will cancel, my hours will
cancel, and I'm left with 345,600/(60*60*24) days. I do that calculation
and I end up with 4 days.
This is an example of my time conversions, and you'll notice that many
times when talking about time conversions there are a lot of different
conversions that might come into play. I might have one conversion factor
when going from hours to minutes or minutes to seconds, but I might have
four conversion factors if I want to go from years to seconds, I might
have three conversion factors if I want to go from seconds to days. Keep
track of where your units are so that they cancel, and you end up where
you want to be.