Physics For Dummies

Because the difference between CGS and MKS is almost always a factor of 100, converting between the two systems is easy. For example, if you know that a ball drops 5 meters, but you need the distance in centimeters, you just multiply by 100 centimeters/1 meter to get your answer: 100 centimeters

5.0 meters #

= 500 centimeters

1 meter

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Note that because there are 24 hours in a day, the conversion factor equals exactly 1, as all conversion factors must. So, when you multiply 1,560 miles/

day by this conversion factor, you’re not changing anything — all you’re doing is multiplying by 1.

When you cancel out days and multiply across the fractions, you get the answer you’ve been searching for:

,

1 560 miles

1 day

65 miles

#

=

day

24 hours

hour

So, your average speed is 65 miles per hour, which is pretty fast considering that this problem assumes you’ve been driving continuously for three days

Always remember to stick with the same measurement system all the way through the problem. If you start out in the MKS system, stay with it. If you don’t, your answer will be a meaningless hodgepodge, because you’re switch-ing measuring sticks for multiple items as you try to arrive at a single answer.