equals 1,000 calories. It is the quantity of heat that will increase the temperature
of 1 kilogram of water by 1 degree on the Celsius scale. Although the calorie is
commonly used, the SI unit for heat energy is the joule. It is abbreviated as J and,
because it is a rather small unit, it is commonly given in kilojoules (kJ). The
relationship between the calorie and the joule is that 1 calorie equals 4.18 joules.
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Because the joule is rather small, kJ is used most often.Scientific Notation
When students must do mathematical operations with numerical figures, scientific
notation is very useful. Basically this system uses an exponential means of
expressing figures. With large numbers, such as 3,630,000., move the decimal
point to the left until only one digit remains to the left (3.630000) and then
indicate the number of moves of the decimal point as the exponent of 10 (3.63 ×
106 ). With a very small number such as 0.000000123, move the decimal point to
the right until only one digit is to the left (0000001.23) and then express the
number of moves as the negative exponent of 10 (1.23 × 10−7).
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Scientific notation is based on exponents of 10.With numbers expressed in this exponential form, you can now use your
knowledge of exponents in mathematical operations. An important fact to
remember is that in multiplication you add the exponents of 10, and in division
you subtract the exponents. Addition and subtraction of two numbers expressed in
scientific notation can be performed only if the numbers have the same exponent.
REMEMBER
Only one digit can be to the left of the decimal point.Examples
Multiplication:
(2.3 × 10^5 )(5.0 × 10−12). Multiplying the first numbers, you get 11.5, and addition