SI Measurements (also known as metric system ) SI stands for System International or International System of Measurement
SI Measurements (also known as metric system ) What about it? Common Language for scientists Based on units of 10 Multiply or divide to go up or down when converting units Prefixes determine how much of a unit Why we use the Metric System clip
SI Measurements (also known as metric system ) Important BASE units to remember: METERS = m (measures distance or length) Measure with ruler/meterstick
LITERS = L (measures volume how much space something takes up) Measure with graduated cylinder/beaker Or with a ruler (length x height x width)
GRAMS = g (measures mass) Measure with triple beam balance/scale
o CELSIUS = o C (measures temperature) Measure with thermometer
Metric Temperature Thirty is hot Twenty is nice Ten is chilly Zero is ice
Important PREFIXES to remember: k = kilo- (means 1000 ) h = hecto-(means 100 ) D (da) = deca-(means 10 ) BASE UNIT (liter, meter, gram) d = deci-(means 1/10 or 0.1) c = centi- (means 1/100 or.01) m = milli- (means 1/1000 or.001)
Easy way to remember the order of prefixes: King Henry Died By Drinking Chocolate Milk Measurement by Brainpop
Heat and Temperature
Introducing!!! - According to the kinetic theory of matter, all matter is made up of tiny particles called atoms or molecules. - These particles are always moving, and it is this movement that helps decide what state of matter exists (solid, liquid, gas, plasma). - The particles have potential and kinetic energy (kinetic as they are moving, and potential as they are potentially attracted or repulsed by each other). - The TOTAL of all these forms of energy in a particular substance is called its thermal energy. (Physicists also call this internal energy because it is internal to a substance).
Temperature - When you strike a nail with a hammer, it becomes warm. Why? When you put a flame to a liquid, the liquid becomes warmer as its molecules move faster. Why? - In both the above examples, the molecules are made to race back and forth faster. In other words, they gain kinetic energy. In general, the warmer an object, the more kinetic energy its atoms and molecules possess. - Temperature, the degree of hotness or coldness of an object, is proportional to the average (NOT total) kinetic energy of the atoms or molecules making it up.
Measuring Temperature - Temperature is expressed quantitatively by a number that corresponds to the degree of hotness on some chosen scale. - The scale most often used world-wide is the Celsius thermometer, where a zero (0) is assigned to the temperature at which water freezes, and 100 is assigned to the temperature at which water boils (at standard atmospheric pressure).
Measuring Temperature - In the U.S., the number 32 is traditionally assigned to the temperature at which water freezes, and the number 212 is the temperature at which water boils. This thermometer is called the Fahrenheit scale.
Upper Limits of Temperature - In principle, there is no upper limit to temperature (There is, however, a theory, called the Planck temperature, that physicists use as an understood upper limit). -As thermal motion increases, a solid object first melts than vaporizes. As the temperature is further increased, molecules dissociate into atoms, and atoms lose some of their electrons, thereby creating a cloud of electrically charged particles called plasma. - Plasmas exist in stars, where the temperature is many millions of degrees Celsius.
Lower Limits of Temperature - In contrast to high temperatures, there is a definite limit at the opposite end of the scale, called absolute zero. - Temperature is based upon kinetic energy of molecules. The colder something is, the slower the molecules. Eventually, the molecules will slow down SO much, they will essentially stop moving (they will be out of energy, and so they can t get any colder).
Measuring Temperature - The absolute temperature scale is called the Kelvin scale. Absolute zero is 0 K. The melting point of ice is 273 K, and the boiling point of water is 373 K. There are no negative numbers on the Kelvin scale.
Formulas, Shmormulas - Here s the part you all LOVE to hate: How to convert from one scale to the other. Fahrenheit to Celsius Celsius to Fahrenheit Celsius to Kelvin Kelvin to Celsius Here's a trick for converting Celsius to Fahrenheit in your head: 1) double the Celsius temperature 2) subtract one tenth of this value 3) add 32 EXAMPLE: let's use 30 degrees C as an example. 1) double the Celsius temperature (2 x 30 = 60) 2) subtract one tenth of this value (60-6 = 54) 3) add 32 (54 + 32 = 86 degrees F)
Quick Side Note - Remember a few slides ago I mentioned Planck s temperature as the possible upper limit of temperatures? Here s the deal: - The highest possible temperature that physicists have theorized (not actually reached, but theorized) is 10^32 degrees Kelvin. For comparison, the center of the sun bubbles along at 15 million Kelvin (15 x 10^6); and silicon can be created by fusion at 1 billion Kelvin (10^9). - The highest possible temperature that physicists have theorized (not actually reached, but theorized) is 10^32 degrees Kelvin. For comparison, the center of the sun bubbles along at 15 million Kelvin (15 x 10^6); and silicon can be created by fusion at 1 billion Kelvin (10^9).