Intro to Physics

Scientific notation is a system that makes it easy to work with the huge range of numbers needed to describe the physical world. Even very large or very small numbers can be simply expressed as a coefficient multiplied by a power of ten. Scientific notation

The coefficient is a decimal number between 1 and 10. Scientific notation Scientific notation is a system that makes it easy to work with the huge range of numbers needed to describe the physical world.

Powers of ten are 10, 10 2 = 100, 10 3 = 1000, 10 4 = 10,000 and so on. The coefficient is a decimal number between 1 and 10. Scientific notation Scientific notation is a system that makes it easy to work with the huge range of numbers needed to describe the physical world.

For numbers less than one, scientific notation uses negative exponents: The number is 1.5 ÷ 1000 = 1.5 × Numbers less than one

Powers of ten

Calculators and computers use the symbol E or EE for powers of ten. The letter E stands for “exponential” (another term for scientific notation). Powers of ten on a calculator

Practice… E e ee x 10 3 joules (4.18 E3) 3.5 x meters (3.5 E-2) Use the calculator to write numbers in scientific notation: a)4,180 joules b)0.035 meters 0.035

1.Express the following numbers in scientific notation: a.275 b c.93,422 d Assessment

1.Express the following numbers in scientific notation: a x 10 2 b x c.93, x 10 4 d x 10 -5

In Physics units are a key to telling you what sort of quantity you’re dealing with. Having the units we use memorized will be vital to your success this year! Unless you’re told otherwise EVERY answer you have this year should have UNITS with it! Units are like clothes for your #’s, we do NOT want any naked #’s! Example  You calculate that a ball traveled a distance of 5 meters. WRONG way to record answer  5 RIGHT way to record answer  5m or 5 meters Importance of Units

The International System of Units

In the SI system, mass has units of grams (g) and kilograms (kg). One kilogram is 1000 grams. Measuring mass

Length is a fundamental quantity. There are two common systems of length units you should know: The English system uses inches (in), feet (ft) and yards (yd). The metric system using millimeters (mm), centimeters (cm), meters (m), and kilometers (km). Length The meter is the SI base unit for length.

Area is a derived quantity based on length. Surface area describes how many square units it takes to cover a surface. All surface area units are units of length squared (for example: m 2 ). Surface area

Volume is another derived quantity based on length. It measures the amount of space, in units of length cubed. (example: m 3 ) Volume

The symbol for density is this Greek letter, rho: ρ Density Density is an example of a derived quantity. It measures the concentration of mass in an object’s volume. Density TowerDensity Tower - video Why did the tower make layers and not mix together?

Solving for Density A delivery package has a mass of 2700 kg and a volume of 35 cubic meters. What is its density? 77 kg/m 3

When calculating derived quantities, it will be important to use consistent SI units. Calculating density For example: If density in kilograms per cubic meter is desired, then the mass must be in kilograms, and the volume must be in cubic meters.

Time Time is a fundamental quantity. The SI unit of time is the second.

When solving physics problems, the units you use must be consistent. You need to be able to convert units to make them consistent. To convert a quantity from one unit to another, multiply by a conversion factor. A conversion factor always has the value of one (1) whether it is right-side-up or upside-down. Converting units

Here are some examples of conversion factors for length. Converting units

To convert from one unit to another, multiply by the appropriate conversion factor. Converting other units Pick the conversion factor that lets you cancel the unit you don’t want, and end up with the unit you want. You’ll always “cancel” things diagonally

Test your knowledge Use the conversion factor shown at right to convert 12 inches to centimeters.

Test your knowledge Flipping the conversion factor upside down lets you cancel the unit you don’t want, and end up with the unit you want.

Converting Fractions Converting values in fractions is a little different Ex 1: Convert 10m/s to cm/s. Ex 2: Convert 10m/s to m/hr.

Example 1 Convert 10m/s to cm/s.

Example 2 Convert 10m/s to m/hr.

Double conversions Convert 10mi/hr (i.e. mph) to m/s

Assessment 1.Which of the following unit conversions is correct? A. B. C.

Assessment 1.Which of the following unit conversions is correct? A. B. C. If this is a final answer, round to the correct number of significant figures.

Suppose this is the formula: But the variable you are asked for is time t. Solving for a variable

Multiply both sides by 2: (To get rid of a fraction you “flip & multiply”) Solve the relationship for time, t :

Solving for a variable Solve the relationship for time, t : Multiply both sides by 2: (To get rid of a fraction you “flip & multiply”) Divide both sides by a :

Solving for a variable Solve the relationship for time, t : Multiply both sides by 2: Divide both sides by a :

Solving for a variable Solve the relationship for time, t : Multiply both sides by 2: Divide both sides by a : Take the square root of both sides: (Square root will get rid of a square)

Solve the relationship for time, t : Solving for a variable Multiply both sides by 2: Divide both sides by a : Take the square root of both sides: (Square root will get rid of a square)