Posts Tagged ‘Fun middle school maths’

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2. You should drink 8 glasses of water a day

July 9, 2013

According to Roy Britt at LiveScience


glass waterglass waterglass waterglass water……….glass water
glass waterglass water
glass water

The claim that you need eight 8-ounce glasses of water a day has been debunked.

Drs. Dan Negoianu and Stanley Goldfarb at the University of Pennsylvania reviewed published clinical studies on the topic and foundno data to suggest people need to stick to the “8 x 8” rule. “Indeed, it is unclear where this recommendation came from,” they write in an editorial in the June 2008 issue of the Journal of the American Society of Nephrology.

The 8 Glasses of Water Myth Busted

 

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6. Hiccup Cure 1: Counting backwards from 100

July 9, 2013

One hiccup cure involves counting backwards from 100.

That’s maths folks! And maths seems a less painful cure than poking yourself in the eyes, drinking water with your nose blocked, drinking water through your nose or putting your fingers in your ears.
hiccup 21

An extensive post on Wiki How notes:

hiccup 8
‘Interestingly, some of these folk remedies are on the correct path by having at least some basis in the science of the hiccup and singultus. With home remedies, the methods that attempt to relax or stimulate the diaphragm tend to be the most effective.’

hiccup 15

Counting backwards from 100 hiccup Cure

not so much busted as

being as good as any other folk remedy.

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9 The Memory of a Gold Fish is 3 Seconds

July 9, 2013

pic 16 goldfish

According to the ABC news this myth was busted by a 15 year old Adelaide school boy named Rory Stokes. He fed his goldfish near a Red Lego brick . The fish started anticipatiing food near the brick. He took it away and replaced it several weeks later. The fish remembered the red brick!!! More here.

pic 17

 

The Memory of a Gold Fish is 3 Seconds Myth Busted

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10. 6 degrees of separation

July 9, 2013

You are, according to mathematicians, 1 degree of separation away from anyone you know. Then two degrees from people they know and son on.

Professor of mathematics Jason Brown explained in the Chronicle Herald, California, how the 6 degrees of separation theory works:

pic 19 holding_hands_six

 For example, suppose that you are or have been acquainted with, say, 400 people. Each of those may know 400 others, giving rise to about 400 times 400, or 160,000 people, you may know in two steps.

Again if each of those individuals knows 400 people, you would only be three steps away from about 400 times 160,000, or 64 million people, and so on.
six-degrees

This is exponential growth.

Assuming we each know 400 people.

x = total number of people involved.

n = degrees of separation

 

x = 400n

If n = 6

x = 4006

x = 4 x 1015

As the population of the earth is only 7 Billion or 7 x 109, it seems likely that we can be linked to anyone else on earth in less than 6 degrees of separation, 4 maybe.

 pic 18sixdegsep

6 degrees of separation Myth busted.

 

Exercise:

Here is an awesome Middle School Maths PDF from PBS MATHONLINE based on Rumours.

It is an excellent introduction to exponential functions.

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Pump Up the volume or Knock, Knock Knockin on Your skull wall!

February 18, 2013

Well, little Mathpiggies, lots of students want to be Sound Engineers. It is time to tell cool middle school students that Sound Engineers NEED maths.

olden days sound guy

According to Salford Uni’s Guide to Decibels:

Just about every piece of audio equipment (microphones, loudspeakers, sound cards, amplifiers, mixers, etc) will have specifications expressed logarithmically (i.e. in dBs).

We don’t want to frighten junior sound engineers with complicated formulae. But we can have a little peak at SOUND ENGINEERING.

Here’s the deal.

You want to be a Sound Engineer like this:

sound engineer 1……………………………………………………………….

Not like this:

Sound engineer 2

Sound is tricky. It is a wave of compressed air travelling through the air to your ear.

It is measured in INTENSITY (Air Pressure per sq m) or Power (eg. Energy carried per sec in, say, Kilowatts).

…………………………………………………………………………..

If you have ever been to a Rock Concert you can feel the pressure of the sound wave of the BASS hitting your chest.

At an ELTON JOHN concert Mathspig could feel BENNIE AND THE JETS POUNDING ON HER CHEST …. COULD HARDLY BREATH.

Elton John

The problem, however, is your ears can detect sound pressure over an astounding range of 1 to 1 trillion. Imagine a volume Dial if we used o to a trillion:Vol dial

The other problem is your ears aren’t accurate. Your ears can detect doubling the intensity of a dripping tap but not doubling the sound of a jackhammer. This is why we can easily damage our hearing. We perceive the loudness as linear when it is not.

sound graph 1

To measure sound volume engineers use Powers or Exponents:

Start with 1 million:

1000000 = 10 x 10 x 10 x 10 x 10 x 10 = 106

we call 6 the index and 10 the base.

Similarly 100000 = 105, 10000 = 104, 1000=103, 100=102, 10=101, 1=100; so why not express numbers from 0 to 1000000 as:

1,2,3,4,5,6.

We use decibels, which are 1/10 th of a Bell to measure sound.

Sound Power RAtion

But the sound intensity as measured in decibels dB is a ratio compared to the Threshold of Hearing (TOH), which is set at 100 = 1. Sometimes the sound intensity is a negative number because there are plenty of sounds below our hearing range. Just ask a dog or a bat.

Over the Threshold of Hearing

This chart is from the excellent Physics Classroom

A noise that is 3B or 30 dB louder than another noise is hitting your ear drums with 103  or 1000 times more pressure. Ahhhhhhhhhhhh!

Here is a typical sound levels chart:

typicalsoundlevelscr

Here is the ear safety chart:Ear Safety Chart

Turn Down the volume Exercise:

First, look at the chart above and compare dB readings. Note: Every 20 dB or 2 B increase in sound intensity increases the sound pressure on your ear drum by a factor of 100.

Now, we are going to convert the sound pressure in dB on the typical sound levels chart chart back from the dB (or log scale, mathpig teachers) to real scale by:

Convert to B by dividing each measurement by 10 and turning into a power and calculating value:

eg Ordinary Conversation:  60 dB = 6.0 B = 106 intensity = 1,000,000

   Rock Band: 120 dB = 12.0B = 1012 intensity = 1,000,000,000,000

If you are interested in simple explanation of volume and Guitar Amplifiers go here:

or here