PHYSICAL SCIENCE UPDATES
 

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What's This Stuff?

page 2:

With nearly two at least three million different kinds of plants and animals on Earth, scientists must devise a method of identifying and understanding the variety of life they study.

page 44:

Other liquids that form bubbles below the surface of the liquid that move slowly through the liquid are "viscous". The bubbles need extra time to move up through the liquid. The bubbles are trapped below the surface of the liquid.

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Long chain molecules exist in your food, such as in ice cream. Xanthan gum, carrageenan and guar gum are all related to sugar and are all made by nature in plants, algae, bacteria, and fungi. They thicken and increase the viscosity of food. Cornstarch and flour have long been used to thicken gravies and soups. Long chain molecules such as glucose are the main component of rice, flour, and potatoes. Other food polymers include: cellulose, pectin, locust bean, alginic acid, and agar.

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The spherical shape of the bubble is the most economical shape requiring the least energy.

page 69

regelation: Phenomenon of ice melting under pressure and freezing again when the pressure is reduced (i.e. ice skating).

On the Move

page 43

There is a force named centripetal. In an ancient language, this means "center seeking". Centripetal force is in a direction opposite to the fictitious centrifugal force.

page 53

If a swing is pulled back farther (has a greater amplitude), it must travel farther to have the same frequency as the swing with less amplitude. The swing with greater amplitude has a stronger pull of gravity and more inertia.

If a swing has more mass (five paper clips, not two), it has more pull from gravity and more inertia once it is moving. The swing with less mass has less pull from gravity, but also less inertia when it is at rest. It is easier to get the swing with less mass to move which balances with the inertia of movement the swing with more mass has.

The only way to get the swings to change frequency is the shorten or lengthen them. If a person blows over the mouth of a bottle, a sound is heard. If water is poured into the bottle, the column of air in the bottle is shortened and the sound is higher. The frequency of the sound is faster greater. This experiment was featured in the second grade physics unit.

It Matters!

page 10

The liquid water is changing state from a liquid into a gas. It is not steam. Steam is water under extreme pressure at 100º C (atmospheric or higher pressure), invisible, and dangerous.

page 16

Explain the difference between steam (at 100º C atmospheric or higher pressure) and water vapor (less than at 100º C atmospheric or higher pressure).

It Works!

A new lesson about the sources of light was added after 9/01. If you purchased your teacher guide prior to 9/01, use the first page number. If you purchased your teacher guide after 9/01, use the second page number.

page 13 or 17: Sound is a form of energy we sense with our ears. Sound vibrations can travel through solids, liquids, and gases but not empty space.

page 13 or 17: Ultrasound is the sound that is above or below the frequencies heard by humans.

page 18 or 22: The faster the waves, the higher the frequency. The higher the frequency, the higher the pitch.

page 53 or 57: James Clerk Maxwell, a British physicist who lived from 1831-1879, was credited with being the first to write down the unifying laws of electricity and magnetism.

page 63 or 67: The magnetic field of the Earth extends nearly 50,000 miles out into space. It is the cause, in combination with charged particles from the sun, of the Aurora Borealis and Aurora Australis.

page 63 or 67: The outer core of the earth is not solid iron, it is a liquid.

page 83 or 87: frequency: Number of vibrations per unit of time

page 83 or 87:

music: Sound made by regular vibrations.

noise: Sound made by irregular vibrations.