Reference point:

• Stand in front of the class and toss a ball up and down.
• "Describe the motion of the ball."
• "If we were going down the road in a school bus, me standing in the isle and you sitting in the seats, would the motion of the ball be different?"
• "If someone was standing beside the road as we passed, what would they see the ball doing?"

Centripetal acceleration:

• Tie a rubber stopper to the end of a string.
• Swing the stopper in a circle at a constant speed.
• "Is the stopper accelerating?"

Momentum:

• Use a 5-ball momentum apparatus.
• "What will happen when one ball strikes the other four?"
• "What will happen when two balls strikes the other three?"
• "What will happen when three balls strikes the other two?"
• "What will happen when four balls strikes the other one?"

Forces and motion:

• Place a book on the table.
• "What forces are acting on the book?"
• Push the book across the table.
• "What just happened?"

• Hold up a baseball and a ping pong ball.
• "Which of these will hit the ground first if they are dropped at the same time?"
• "Hold up the baseball and a piece of paper.
• "Which of these will hit the ground first if they are dropped at the same time?"
• Crumple the paper into a ball and drop them.

Projectile motion:

• Take the class outside with a baseball.
• "Who can throw the baseball the greatest distance in the air?"
• Give class members a chance to throw the ball.
• Mark the greatest distance.
• Discuss the difference in the flight of the ball.

With the balloon inflated, hold the frame over a pillow. Hold the frame straight out at chest height. Ask students to predict what will happen when you release the frame. Guide them to specifics such as where in the fall will the balloon pop. Release the frame. The balloon will pop almost instantaneously. The balloon pops because the weighted pin becomes weightless. The rubber bands are essentially pulling against nothing. This means the rubber bands pull the pin up into the balloon.

Air pressure:

• Place a small amount of water in an aluminum pop can.
• Heat the can until steam is visible coming out of the can.
• Quickly invert the can into a pan of tap water.
• Pressure immediately crushes the can.

• Hold a piece of paper just under your mouth and blow across the top of the page.
• The paper will rise because of the difference in air pressure above and below the page.

• Hang two apples from a horizontal bar.
• The apples should be about an inch apart.
• Blow between the two apples.
• The apples move toward each other because of the difference in air pressure.

Work:

• Walk over to the classroom wall and push on it.
• "Am I doing work on the wall?"
• Why?

Simple machines:

• Have several common "tools" laying on a table.
• Tools could include a hammer, screwdriver, scissors, pliers, crowbar, door knob, etc.
• Have students identify the type of simple machine for each tool.

Kinetic and potential energy:

• Place a book on a table.
• "How much energy does this book have?"
• Lift the book above the table.
• "How has the energy of the book changed?"
• Drop the book back onto the table.
• Discuss changing potential energy into kinetic energy.
• Account for the sound made when the book struck the table.

Charles' law:

• Seal a small ziplock bag with a little air in it.
• Place the bag in a container of boiling water and observe.

Thermal expansion:

• Use a "ball and ring" apparatus.
• Show that the ball will not pass through the ring.
• Heat the ring in a flame.
• The ball will now pass through.

• Invar is an alloy containing 36% nickel. It is used in the manufacture of precision instruments because of its low coefficient of expansion.
• A bimetallic strip is brass on one side, bonded to invar on the other.
• The strip is straight at room temperature and curves when heated.

• Use enough water to half fill an unwaxed paper cup.
• Place the cup over a lab burner and boil the water.
• "Why doesn't the paper cup burn?"

Volta's pile

In the 18th century, an Italian scientist, Count Alessandro Volta proved that an electric current is made when two different metals are separated by something moist. This demonstration re-creates Volta's experiment.

• Start with six copper pennies (pre 1984).
• Cut five pieces of blotting paper (filter paper), each the size of a penny. Soak them in salt water.
• Cut six pieces of aluminum foil, each the size of a penny.
• Begin with a penny and stack the "pile" in this way:

  Cu/Al/paper/Cu/Al/paper/Cu/Al/paper/Cu/Al/paper/Cu/Al/paper/Cu/Al

• Hold the "pile" between two moist fingers. If you do not feel a slight tingle in your fingers, touch your tongue to the "pile".

Transverse and longitudinal waves:

• Use a wave spring to demonstrate longitudinal waves.
• Use a "slinky" to demonstrate transverse waves.

• Tie a tuning fork securely to a heavy cord.
• Strike the tuning fork.
• While it is vibrating, swing the tuning fork in a horizontal circle.
• Students will hear a change in pitch as the tuning fork travels around the circle.

Excited atoms:

• Rub the side of a fluorescent tube with saran wrap.
• When the weather is dry enough to let the charge build, the phosphors in the tube will glow.
• Touching the saran wrap to the end of the tube might produce flashes of light.

• Place a straight rod (pencil) in a beaker of water so that part of the rod sticks above the water.
• Look at the rod from the side of the beaker and the top of the beaker.

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