Question about physics ?

Question

I've missed a few days of my first year of physics and I've missed the most important part.

I don't understand how to convert units.

Like for example, one of the questions is:

"Express each of the following as indicated:

a. 2 dm expressed in millimeters

b. 2 h 10 min expressed in seconds

I know that there is the little saying

Kids Have Dropped Over Dead Converting Metrics

...but idk wut they stand for

im just totally lost.

can anybody help me?

plz

Answer 1

Google a metric table and memorize it.  The prefixes are standard for any measurement.  It is a good thing to understand metric and will speed up your calculations.

Answer 2

a. 2 dm expressed in millimeters

This is one you'll only run into as an exercise in a book.  Nobody uses deci- or hecto- or deka- as far as I know in real life.

But a decimeter (dm) is a tenth of a meter and a millimeter is thousandth of a meter, so there are 100 millimeters in a decimeter.  So, 2 dm = 200 mm.

b. 2 h 10 min expressed in seconds

This is more real-life.  You need to remember there are 60 seconds in a minute and 60 minutes in an hour.  That makes 60*60 or 3600 s in an hour.

2 h 10 min is 2*3600s +10*60 s= 7800 s