Extra credit (a total of something like 40 pts, out of which a max of 25 pts may be applied to exam totals)

5 pts problem 9-82. p. 293 Crab nebula pulsar slowing down. Find I and then pulsar radius. Compare to density of a nucleus.

5 pts problem 9-85 p. 293. Properties of a CD disc.

10 pts. Use the air track and PVC pipe to predict acceleration at which pipe will topple over. Confirm or deny the prediction with a measurement on the air track. Sketch setup, provide details.

10 pts. Given two materials with different thermal expansion coefficients, design a pendulum whose distance from pivot to the center of mass will not change with temperature. Materials could be iron and brass, or others. [This is what a guy did successfully in the early 1700s trying to build an extremely accurate clock for use in navigation. Maybe you saw the series on public TV; it may have been called 'Navigation' or some such thing.]

10 pts Given a pressure gauge running from 0-1 atm, design a fluid-filled accelerometer good
from 0-1 g,

5 pts explain the operation of a hydraulic impulse pump, placed in a stream, which
automatically feeds water to a much higher elevation. No power required for this pump,
supposedly invented in the late 1700's by one of the Montgolfier brothers.

5. 14-91 shape of a falling stream of water.

10. Invent a pair of 'water shoes', equivalent to snowshoes, for walking on water. These
would be based on surface tension. You might want to look up how some bugs walk on
water, to get some ideas on this.

10. Predict the rate at which water will leave a small circular hole in the bottom of a
container. Measure this rate using a force meter to track the weight as a function of the time as
the water leaves the container. Compare the two.