9TH Grade Science [Earth Science] 


Prefix  Abbreviation  Meaning  Example 

mega  M  10^{6}  1 megameter (Mm) = 1 x 10^{6} m 
kilo  k  10^{3}  1 kilogram (kg) = 1 x 10^{3} g 
centi  c  10^{2}  1 centimeter (cm) = 1 x 10^{2} m 
milli  m  10^{3}  1 milligram (mg) = 1 x 10^{3} g 
micro  μ  10^{6}  1 micrometer (_{μ}g) = 1 x 10^{6} _{μ}g 
nano  n  10^{9}  1 nanogram (ng) = 1 x 10^{9} g 
Example 1  Example 2  
With this method, you can easily and automatically convert very complex units if you have the conversion formulas. The method involves the following steps  Convert 6.0 cm to km  Convert 4.17 kg/m^{2} to g/cm^{2} 
1. Write the term to be converted, (both number and unit)  6.0 cm  4.17 kg m^{2} 
2. Write the conversion formula(s)  100 cm = .00100 km  1.00 m = 100 cm 1.00 kg = 1000 g 
3. Make a fraction of the
conversion formula, such that a) if the unit in step 1 is in the numerator, that same unit in step 3 must be in the denominator. b) if the unit in step 1 is in the denominator, that same unit in step 3 must be in the numerator. Since the numerator and denominator are equal, the fraction must equal 1. 
.00100 km 100 cm 
1000 g 1.00 m 1.00 m 1.00 kg 100 cm 100 cm 
4. Multiply the term in step 1 by the fraction in step 3. Since the fraction equals 1, you can multiply by it without changing the size of the term.  6.0 cm .00100 km 100 cm 
4.17 kg
1000
g 1.00 m 1.00 m m^{2} 1.00 kg 100 cm 100 cm 
5. Cancel units  6.0 100 
4.17 
6. Perform the indicated calculation rounding the answer to the correct number of significant figures.  .000060 km or 6.0 E 5 km  .417 g cm^{2} 
1.0 in 20 cm  = 7.87 in 2.54 cm

How does the greenhouse effect work?
Thus greenhouse gases absorb radiation from earth's surface, and reradiate
most of it back to the surface, keeping the surface warm. If there were
no greenhouse gases, the surface would rapidly radiate heat away to space.
2.2  Weather and Climate
In simple terms, weather is what happens outside. The air, or atmosphere, around us behaves in different ways.
It changes when it's hot or cold, and when it's wet or dry. It acts differently when it's calm or stormy, and clear or cloudy.
The atmosphere reacts to everything from rain to sunshine. Sometimes the atmosphere behaves violently, and sometimes it's peaceful and quiet.
Climate is the average weather in a location over a long period of time. A place that doesn't get much rain over many years would have a dry climate.
A place where it stays cold for most of the year would have a cold climate. Climate helps determine when the best time would be for farmers to plant their crops.
Although an area's climate is always changing, the changes do not usually occur on a time scale that's immediately obvious to us.
While we know how the weather changes from day to day, subtle climate changes are not as readily detectable.
Weather patterns and climate types take similar elements into account,
The temperature of the air is directly related to the amount of energy which is derived from the sun's solar radiation.
The higher the temperature, the higher the amount of energy in the air. Temperature is measured using a thermometer with units in degrees Celsius or Fahrenheit.

