Measurements in Science & Scientific Notation

Differences in Measurement Qualitative Measurements – a description using words about an observation Color, smell Quantitative Measurements – mathematical equations, measured amounts A = l x w V = l x w x h

Advantages to Quantitative Measurements Numbers are universal- they are known throughout the world Languages are not- many language barriers You can communicate with everyone with numbers

Accuracy vs. Precision

Precision Precision - ability of a measurement to be consistently repeated. Ex. A thermometer measures the same temperature of a liquid 5 times Ex. A gun hits the same place on a target every time

Accuracy Accuracy - ability of a measurement to match the actual value of the quantity being measured Ex. A thermometer measures the exact temperature of a liquid Ex. A gun hits the bull’s eye on a target

Roles in Science It is important for science to strive to be both precise and accurate We cannot be more precise or accurate than the instruments we are using Ex. A ruler can accurately measure out to 2 decimal places Ex. 2.54 inches We could not get a reading of 2.543577 inches from a ruler

Mass vs. Weight Important to note that these are not the same thing! Mass – the amount of matter in an object In space, the more mass an object has, the more gravitational attraction it has Weight – a measure of the gravitational force exerted on an object Being on a different planet would give you a different weight Ex. The Moon’s gravity is about one-sixth of Earth’s. So you would weight about 1/6 of your current weight on the Moon

Mass/ Volume/ Density Don’t be fooled! Which has a greater mass a kilogram of bricks or a kilogram of feathers? Mass: the amount of matter in something Measured using a balance or scale (g) Volume: the space something takes up Calculated by formula or displacement (L or cm3) Density: How much stuff (mass) can fit in a certain amount of space Density = Mass/Volume or D= m/v (g/mL or g/cm3)

Scientific Notation We use this to write out very large numbers and very small numbers Ex. The distance from Earth to Pluto is 4,500,000,000,000 m. This number would be annoying to work with so we use a different form

Steps for Scientific Notation Changing from a regular number into scientific notation form 1st – move the decimal point to make a number between 1 and 10 Count the number of decimal places that you moved Decide if you moved in a positive or negative direction If moving the decimal makes the number smaller, it is going to have a positive exponent If moving the decimal makes the number BIGGER, it is going to have a negative exponent

Example 5,000,000 We move the decimal place 6 places to the left to make the number 5 Our number got smaller as we moved the decimal point so we will have a positive exponent Our new number is 5 x 106

Examples 1. 6,000 2. 35,000,000 3. 0.0056 4. 0.0000009 5. 0.000123 = 6 x 103 = 3.5 x 107 = 5.6 x 10-3 = 9 x 10-7 = 1.23 x 10-4

Changing from Scientific Notation to a Regular Number Determine how many places you must move the decimal (based on the exponent) Determine which way to move decimal point Right for a positive exponent (number must get bigger) Left for a negative exponent (number must get smaller)

Examples 1. 3 x 102 2. 6 x 105 3. 5.5 x 103 4. 3.4 x 10-2 5. 9.9 x 10-3 = 300 = 600,000 = 5500 = .034 = .0099

More Practice Solve and Answer in Scientific Notation 1. 6,000 x 1,000 2. 8,000 x 500 3. (6.5 x 102) (3.2 x 104) 4. (2.1 x 103) (6 x 104) 5. (7.5 x 10-4) (1 x 10-3) = 6 x 106 = 4 x 106 = 2.08 x 107 = 1.26 x 108 = 7.5 x 10-7

Exit Ticket #9-12

9. If you measure the volume of a container and get the same answer 4 times in a row, this is an example of: Accuracy Precision Correctness Luck

10. If you measure the volume of a container and get a recording of 10 10. If you measure the volume of a container and get a recording of 10.2 mL and the actual volume is 10.2 mL, this is an example of: Accuracy Precision Correctness Luck

11. If you travel to the moon, because of a change in gravitational force, this will change: Your volume Your height Your mass Your weight

12. This a measure of the total amount of matter in something, despite the force of gravity: Volume Height Mass weight