Subject: Physics    / General Physics
1.    Air in a cylinder is compressed to one-tenth of its original volume without change in temperature. What happens to its pressure? Imagine now that a valve is opened in order to restore the initial pressure value. What percentage of the molecules has escaped?

2.    Consider a 40,000 km steel pipe in the shape of a ring that fits snuggly all around the circumference of the Earth. We are heating now the ring so its temperature increased by 1 degree C. Now, the pipe will no longer be snug. How high the ring will now stand above ground level? (Make as many simplifications as necessary). Data: Coefficient of linear expansion for steel is 11*10-6 /degree C. This means, for example, that a 1-meter bar of steel that increases its temperature by 1 degree C will expand 11*10-6 meters (11 micrometers)

3.    Farmers resort to spraying fruit trees with water before a frost to protect the fruit from freezing. Using the concepts learned in this module, discuss why this does or does not work.

4.    An electric fan not only does not decrease the temperature of the air, but it actually increases air temperature. How can you then explain that you are cooled by a fan on a hot day?

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