GOOD MORNING!! WARM UP: (Put directly underneath PICK UP: Calculator, Small Review Book TURN IN: Lab, if you didn’t yesterday REMINDERS: Bring pennies!! App: ConnectED Mcgraw Username: txchemistry2014s Password: lonestar1 WARM UP: (Put directly underneath your 2.2 Notes from last night) Page 11: # 13 (a-f) Page 13: #15 (a-f) Page 14: # 16, 17, 18, 19

Scientific Notation

What is scientific Notation? Scientific notation is a way of expressing really big numbers or really small numbers. It is most often used in “scientific” calculations where the analysis must be very precise.

Scientific notation consists of two parts: A number between 1 and 10 A power of 10 N x 10x Are the following in scientific notation?

Changing standard form to scientific notation.

To change standard form to scientific notation… Place the decimal point so that there is one non-zero digit to the left of the decimal point. Count the number of decimal places the decimal point has “moved” from the original number. This will be the exponent on the 10.

Continued… If the original number was less than 1, then the exponent is negative. If the original number was greater than 1, then the exponent is positive.

Changing scientific notation to standard form.

To change scientific notation to standard form… Move the decimal point to the right for positive exponent. Move the decimal point to the left for negative exponent. (Use zeros to fill in places.)

Using Scientific Notation in a Calculator When entering scientific notation in the calculator, we use the “ee” button. 3.0 X 1023 is entered the following way: 3.0 “ee” 23

Dimensional Analysis

How Many Seconds are in a day? First of all: DON’T PANIC. This is only a difficult problem if you think about it as a whole. Break it up into small parts! The first question you need to ask is: What do I KNOW?

How many seconds are in a day? What do we know? All of these statements are TRUE or equivalent Next Question: What do I NEED ?

How many seconds are in a day? Now remember, we’re trying to get to seconds per day: OR So….let’s start with the first thing we know…..and work our way through it. Step by Step.

How many seconds are in a day? So we end up with: Or, 86400 Seconds in a day. You don’t ever need to worry about the units….if you set it up the right way, you will get the right answer EVERY time!

Another example…. How many hours in a year?

Another example…. How many hours in a year? OR: Why are these slightly different?

If you are going 50 miles per hour, how many feet per second are you traveling?

In the yearly fundraiser at school, kids can earn an ipad if they raise at least $300 in donations. James was able to get all of his family and family friends to pledge enough money that he will earn $30 for each mile he runs. James runs 90 inches per second. How many hours will it take him to run just long enough to earn his ipad?