Make Your Own Clock Faces

October 10, 2011

Marty Sagendorfby: Martin Sagendorf

A Definition:

Clocks measure time – it can be a continuous measure of events passing or the measure of the interval between two events.

Of Hours:

After years of evolution, our modern clocks now divide the day into 24 equal length hours.  And, as we know, there are two systems in use today: Americans use the “double-twelve” system while the rest of the world uses the 24 hour system.

As An Aside:

The word “hour’ comes from the Latin and Greek words meaning season, or time of day.  A “minute” from the medieval Latin pars minuta prima (first minute or small part), originally described the one-sixtieth of a unit in the Babylonian system of sexagesimal fractions.  And “second” from partes minutae secundae, was a further subdivision on the base of sixty – i.e. “a second minute”.  (ref. Pg. 42 The Discoverers by Daniel J. Boorstin)

The “Double-Twelve” Clock Face:

Has 12 at the top – probably because at noon the sun is at its highest point in the sky.

But…

We can make a clock with 12 o’clock anywhere we wish and the clock will still work just fine. Read the rest of this entry »

2 Comments | Chemistry, College level, Elementary level, High School level, Middle School level, Physics | Tagged: , , , | Permalink
Posted by Tami O'Connor

The Law of Dulong and Petit

September 3, 2011

by: Dr. Jean Oostens

Atoms were proposed in antiquity without any experimental evidence by Democritus, a Philosopher.  This must have been a problem for Newton and Leibnitz who posited that there was always a mean of considering smaller and smaller intervals of space to calculate the “instantaneous velocity”.

The introduction of the precision balance in chemistry by Lavoisier paved the way for Dalton to formulate his laws on the “definite and multiple proportions” governing chemical reactions.  This supported the atomic theory, without giving it general acceptance.

Specific heat was defined as the quantity of heat needed to increase one gram of a substance by one degree.  There was no definite pattern when specific heats of various substances were compared.  Until two French scientists in 1819 calculated specific heat by atomic mass, forming the Law of Dulong and Petit.  There appeared a number of cases where the results were quite similar: about 6 calorie per mole.  This was equivalent to stating that any atom is as good as any other to store heat!  This was a small step towards acceptance of the existence of atoms.   An explanation for this, and the reason for the exceptions, had to wait the early 20th century explanation by Albert Einstein.  By that time, atoms had gained wide acceptance from the work of Rutherford, and soon by Bohr.

Lesson on the Law of Dulong and Petit:

You are given several chunks of metal, each containing 0.6 * 1024 atoms (i.e. one mole) of one element.   How will each of those samples, when dropped in a standard quantity of hot water (typically 200 mL and 70 C) affect the temperature?

Step 1.  Use a good balance (at least 0.1 gm resolution) to determine which element you are dealing with.  If possible confirm your identification with an additional cue. Read the rest of this entry »

1 Comment | Chemistry, College level, experiments, High School level, Physics | Tagged: , , , , | Permalink
Posted by Tami O'Connor

How to Make a Rocket (Scientist)

July 1, 2011

Tami O'Connor, Educational Innovationsby:  Tami O’Connor

A few months ago I had occasion to conduct two hands-on workshops for elementary and middle school teachers at the NSTA National Convention in San Francisco on behalf of Educational Innovations.  One presentation focused on film canister rockets.  This is a tried-and-true way to teach Newtown’s First and Third Laws of Motion and also brings to light concepts such as the four forces of flight; thrust, drag, weight, and lift.  It also reinforces instruction on 3-D shapes and 2-D plane figures such as circles, cones, cylinders, rectangles, and triangles.

How to Make a Rocket Scientist - Educational Innovations BlogI presented the lesson to the teachers in much the same way I would to my students.  The first thing we did was to brainstorm the features all rockets have.  After a bit of discussion it was agreed that they all have a nose cone, a cylindrical body, fins, and an engine.  I then handed out a paper template imprinted with the pattern of a nose cone and fins, a regular 8½ x 11 sheet of white paper, a piece of goldenrod paper, and a white translucent film canister.  Also required are scissors, tape, ¼ piece of an Alka Seltzer tablet, and paper towels.

The only canister that works with this rocket is the type that has the lid that fits snugly inside the canister.  The canisters that have a lid that wraps around the outside rim, however, will not allow enough pressure to build up inside the chamber.

How to Make a Rocket

The first step in building a film canister rocket is to construct the body of the rocket.  The easiest way is to curl the white 8 ½ x 11 paper into a cylindrical shape using the film canister (without the top) as a guide.  The paper can be rolled around the film canister and then taped along the edges.  The easiest way to recover the film canister is to blow into one end of the rolled cylinder, forcing the canister out the other end. Read the rest of this entry »

3 Comments | Chemistry, Elementary level, energy, experiments, High School level, Middle School level, Physics | Tagged: , , , , , , , , , , | Permalink
Posted by Tami O'Connor

Silicon from Sand

March 2, 2011

by: Carl Ahlers

Next time you step onto the beach, bend down, grab a handful of sand and admire the fact:   By mass 47% of what you hold in your hand is the element silicon. The rest is simply oxygen.  Remarkable!

Silicon is the second most abundant element in the earth’s crust (27.7%) – only oxygen beats it – and can easily be extracted from white sand (SiO2) in a spectacular reaction in the school science laboratory. Read the rest of this entry »

6 Comments | Chemistry, College level, experiments, High School level | Tagged: , | Permalink
Posted by Tami O'Connor

No-Pop Bubbles!

December 3, 2010

Ron Perkins, Educational Innovationsby Ron Perkins

At first glance No-Pop Bubbles may seem like any other bubbles.  While the bubble solution is a bit more viscous, one blows No-Pop Bubbles like any other bubble.  The small bubble wand suspends a bubble film which, when air is blown through it, releases small bubbles into the air.

These bubbles, however, are no ordinary bubbles.  No-Pop Bubble solution begins as a regular soap and water bubble solution.  Added to this solution is a small amount of a non-toxic water soluble polymer.  When No-Pop Bubbles are first blown, the bubbles behave like ordinary bubbles.  As the water evaporates from the bubble’s surface, however, an extremely thin plastic ‘bubble skeleton’ remains.  It is this plastic bubble skeleton which has the properties for which No-Pop Bubbles are named. Read the rest of this entry »

6 Comments | Chemistry, density, Elementary level, experiments, High School level, Middle School level, static electricity | Tagged: , , , | Permalink
Posted by Tami O'Connor

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