Time and length are the most common units of measure. Since the early eras, cultures have used the sun for their time. But in our modern era time is more precise. How does time become so precise? Scientist use the atomic clock. The atomic clock uses a precise microwave that measures the energy difference between two cesium atoms. One second in measured to about 9 billion cycles of microwave radiation on that atom. There's something you don't learn everyday.
A common problem for many students, I included, struggle with remembering to insert units to our answers.
For example, lets say you put 1 as your answer. 1 what? 1 apple? 1 water bottle? A physics student must include his or her units. This is imperative. You will get marked off if you don't include units.
Units must be dimensionally consistent. By that I mean you cannot add buildings and broccoli together. If you have a time and a distance you can measure that, by the equation d=vt. Or a speed and a time which gives you distance.
Let's do some practice units.
How many grams are in a kilogram?
How many nanoseconds are in on second?
Answers further down on the page.
There are two different standards of measure. The SI and the US measure system. For our purposes we will be using the SI. Kilogram, meter, and liter are all examples of the International System.
There are 1,000 grams in one kilogram
There are 10^9 nanoseconds in one second
Questions
Email me at mjacks66@msudenver.edu
Mark Jackson
Student Metropolitan State University of Denver
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