What’s Goin’ On In Room 133

Posts Tagged ‘algebra’

Colleagues, I am sure that you have seen the news about the devastating earthquake that hit the island country of Haiti this week.   Sadly, many thousands of lives were lost because it hit a region where more than 3 million people live.  The full extent of this tragedy will not be known for a long time.  Homes, schools, churches, roads, bridges – so many things that we take for granted in life were completely destroyed in seconds and an untold number of families had their lives ripped apart.  This is a very painful time for anyone with family or friends in the area – please be mindful.

Earthquakes are a natural phenomenon on this planet and there is nothing in our power that can stop one from happening.  But wouldn’t it be a good thing if we could at least predict when one is going to happen?  So that at least we can take steps to warn others?  And wouldn’t it be a good thing to build homes and buildings that would not collapse if and when an earthquake does occur?  Well, engineers are studying those very questions – and Math is helping them find answers.

Hear from those who are working on this problem.

See the Presidential Palace before and after the earthquake.

A quick look at what we know so far!

Not your regular Weekend Word Problem, is it?  True.  Sometimes we need to take a moment and put things in perspective.  A lot of times we ask “Why are we studying this?”  This is one of those times when I can tell you that there is only one reason to study math and that is to DO SOMETHING WITH IT TO MAKE LIFE ON THIS PLANET A LITTLE BETTER!  It doesn’t matter what scale you succeed on, Colleagues – the real success is that you try!  

And now for our problem:  Scientists determine the epicenter of an earthquake by measuring the time it takes for surface waves to travel between two places.  Surface waves travel about 6 kilometers per second through Earth’s crust.  (The “quick look” above shows you what this is like.)  Let’s say the distance between Los Angeles and Phoenix is about 600 kilometers.  First, write a multiplication equation to find how long it would take surface waves to travel from Los Angeles to Phoenix.  Then solve the equation.

POST UPDATED ON JAN 14th (Thu)

Just to keep you abreast, Colleaugues, here’s the homework that we laid out this week.

Math 7 – MONDAY:  You had page 153, Ques 1 – 4.   TUESDAY:  Your assignment was to Read and Study Section 4-2 (Solving Addition and Subtraction Equations) on pages 156-158.  Then do even-numbered questions 4 – 24.  THURSDAY:  Textbook page 162, Ques 14, 15 and 16.

Enriched Math – MONDAY:  You had page 21, Ques 49 – 52.  TUESDAY:  your assignment was to Read and Study Sec 1-4 (Properties) on pages 23-27.  Then do even-numbered questions 14 – 34.  THURSDAY:  Textbook page 31, even numbered questions 30 – 40.

You all know that Writing Prompt #9 is due this Friday in your Math Journal.  Points will be LOST for not having one by now.  Rock on Collegues!

The final speed of a falling object is found by using the expression v + 9.8t, where v is the speed when you begin timing and t  is the length of time the object falls.  Find the final speed when the object starts falling at 3 meters per second and falls for 2 seconds.  (Oh, we’re getting into it now, baby!)

UPDATED Dec 6, 2009:  And for a real easy one – check this out.   This problem has nothing to do with the speed problem above; this problem is “ripped from the headlines”!  It’s all about money, secrecy and good old government spending!  

Right now, President Barack Obama is having a tough time getting Congress to cough up billions (some would say trillions!) of dollars to take care of Americans at home.  Well, just over 200 years ago, President Thomas Jefferson had to “sneak around” to get Congress to make another major commitment as well, but what he had in mind was Americans pulling up stakes and leaving their homes for the Great Unknown. 

What was this about?  President Jefferson wanted Congress to fund the 8,000-mile expedition of Meriwether Lewis and William Clark.  It took (that is, the expedition took)  28 months to complete and it “provided the US government with its first glimpse of the vast lands that lay west of the Mississippi River”, according to the good folks at the National Archives.  And how much did President Jefferson want?  No less than the unholy sum of $2,500! 

Check out the SECRET LETTER from Pres Jefferson to Congress asking for the green!

So, the Word Problem is: How much did the Lewis & Clark Expedition cost per mile?  How much did it cost per month?  Do you think we got our money’s worth?  Rock on, colleagues!

Solve each problem by first writing and equation that fits.  You may even want to draw a simple diagram to illustrate the dynamics involved.  Then solve the equation.

EQ 1.  Addie has $825 in her savings account.  She has decided to deposit $65 per month until she has a total of $1,800.  In how many months will this occur?

EQ 2.  YeVale likes skydiving.  Suppose she jumps from an airplane (a perfectly good airplane, mind you) at an altitude of 12,000 feet.  After 42 seconds, she reaches 4,608 feet and she opens her parachute.  What was her average velocity during her descent (freefall)?

EQ 3.  The water level of Lambert Run has risen to 4 inches above its flood stage.  If it continues to rise steadily at 2 inches per hour, how long will it take for the river to be 12 inches above its flood stage?

Rock on, colleagues!

Suppose each student needs 12 minutes to give a report on their project and the class period is 48 minutes long.  How many students will be able to give their report in one class period?  Can you figure that out?  Pretty easy, huh?   Well, what if we let the variable “s” represent that number of students – can you write a simple equation that will fit this example?  

And speaking of food (okay, so I was thinking of food – I’m hungry :0!), suppose one pound of ground beef makes four hamburger patties.  Can you calculate how many pounds of beef would you need make 36 hamburgers?  Sure you can!  Then try writing and solving an equation that fits where you use the variable “x” to represent (or equal = ) the number of pounds of hamburger you need.

Now don’t let those words ”solving an equation” scare you – if it does at all.  You know the answer to the question already just by mathematical reasoning.  So if you can do that, you’ve got the basics down pat.  We’ll talk about how to put that in algebraic form when you show me your work next week!

Gloria’s Furniture Rental store charges a down payment of $100 and $75 per month for a table.  Matthew paid $550 to rent the table.  

So solve 75n + 100 = 550 to find the number of months Matthew rented the table.

Meanwhile, in a room above Gloria’s store, Jamal has to stuff 1,000 envelopes with advertisements.  He can stuff 12 envelopes in one minute, and he has 112 envelopes already finished. 

So solve 1,000 = 12n + 112 to find how many minutes it will take Jamal to handle his business!

Ask the, uh, older folks in your house if they remember the old rock and roll song that goes “Gimme three steps, gimme three steps, mister…”  Then, while they go wandering around playing ”name that tune” in their heads, you can click on the link below and check out a cool video on two-step equations.  There you’ll meet Tim and Moby on BrainPop and they’ll tell you all about it.  (The equations, yo; not the song!)

Anyway, log in as “walkergrant” and use the password “wgms”.  That will take you to the opening screen where you’ll see Moby’s hand counting down to the start of the movie.  And when it says “Click here to start the movie”, well, click it!

http://www.brainpop.com/math/algebra/twostepequations/

Oh, as for your folks, you can tell ‘em it was by Lynyrd Skynyrd on their first album (”pronounced ‘leh-’nerd ’skin-’nerd”) back in 1973.  You know, when you feel like it.

MAJOR UPDATE, YO!  Extra credit on your mind?  Trying to make up for that missing assignment somewhere?  Try taking the Quiz at the end of the movie.  It’s only 10 questions – and you get a chance to email the results to yourself (or me at medwards@cityschools.com) or print them off so that you can bring it in.  Either way, it’s free points, yo!  –mr e

We know about different types of expressions now – first verbal, then numeric and now we know what an algebraic expression is.  We also know how to substitue values (plug in numbers) and evaluate our algebraic expressions if we are told how much ’x’ is equal to.   We’ll practice with the idea of having a letter variable in our calculations a little more by looking at questions #31 and 32 on page 20.