Project 2.1 Hydrogen

Options:

• Write a brief report on the Hindenberg,describe how it was constructed and give reasons for the use of helium instead of hydrogen in large balloons.
• Write a brief report (2 pages) on dirigibles and blimps.
• Design and build a model balloon that can be used to transport small loads.

THE HINDENBERG
The Hindenburg was an airship that caught fire in 1937 while docking in Lakehurst, New Jersey. It had a lifting force of 236 tons. It was launched in 1936 and had completed ten and one-half round trips between Germany and the United States before burning in 1937. Crossing the Atlantic took about 50 to 60 hours.

DIRIGIBLES AND BLIMPS
Graf Zeppelin, a smaller hydrogen airship, had made 650 flights. More than 18,000 passengers were delivered safely during the nine years that the Graf Zeppelin flew. It flew 144 flights nonstop to and from Berlin across the Atlantic to Rio de Janeiro or New York.

Project 2.2 Make a Cartesian Diver

Soda Bottle Physics: The Cartesian Diver
A very simple Cartesian diver can be made using a 2-liter soda bottle and a condiment packet. Place the condiment packet in the bottle and fill the bottle completely with water.

If the packet sinks in the water, select a different packet.

The volume of air inside the packet can be changed by squeezing the bottle. As the volume decreases, it loses buoyancy and sinks. when the pressure is released, its volume should increases again and float to the top.

An eye-dropper partially filled with water also works well. You will need to experiment with the initial volume of air in the dropper.

Project 2.3 Freeze Hot Water and Cold Water

Options:

• Write a brief report on the Mpemba effect. Give possible reasons for this phenomenon.
• Investigate the Mpemba effect by testing the rates at which similar samples of hot and cold water freeze when placed in a freezer.

The Mpemba effect is named after a Tanzanian student who observed that hot water tends to freeze faster than cold water under the same conditions. He observed this while making ice cream and raised the question in 1969.

Project 2.4 Stirling & Other Engines

Options:

• Write a brief report (2 to 3 pages) the history, design and possible uses of Stirling engines.
• Build a model Stirling engine based on a test tube and some marbles.
• Write a report (1 to 2 pages) on the different types of model Stirling engines that can currently be purchased.
• Demonstrate the operation of a small internal combustion engine used in model airplanes – or small pieces of equipment such as lawn mowers or line trimmers.

Sterling Engines

A Stirling engine has a sealed cylinder with different temperatures at each end. The gas inside the engine (which is often air, helium, or hydrogen) is moved from the hot side to the cold side. When the gas is on the hot side it expands and pushes the piston in one direction. When it moves back to the cold side it contracts and moves the piston in the opposite direction.

In the 1970’s, when oil prices soared and appeared to continue to do so, Ford, GM, and

American Motors Corp. spent millions of dollars developing Stirling engines for cars. Ford even built a Stirling that could drive away from the curb (with relatively low power) twenty seconds after you turned the start key.