PAL 3/7/12

1. PAL 3/7/12 • Identify each of these quantities as extensive or intensive: • Temperturature • Pressure • mass • number of moles • Volume • Density • Specific volume • Energy • phase • Entropy • As the temperature increases, do more or fewer balls float. Why?

3. Put a straw in glass of water. When the straw is open to the air, the pressure at the top of the liquid in the straw is atmospheric pressure. Put your thumb over the straw to trap the air in the straw. Now lift the straw partway up the depth of the water – higher than it was, but still submerged • Is the pressure at the top of the liquid in the straw still atmospheric pressure? higher? lower? • Does the level of the liquid stay the same, rise, or lower in the straw as you raise it? (Hint: Think about whether the trapped air expands, contracts, or stays the same to make the pressure change you answered in part 1).

4. Now let’s approach this quantitatively. Be sure to check that your quantitative answer agrees with your qualitative answers to 1 & 2. • Estimate the depth at the bottom of the straw. Find the gauge pressure in the liquid at the bottom of the straw based on the fact that the top of the open fluid in the glass is at atmospheric pressure. • Estimate the depth of the fluid in the straw. Find the gauge pressure of the fluid at the top of fluid in the straw, based on the pressure at the bottom of the straw found in part 3. Is this higher or lower or the same as atmospheric pressure?