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Physics 223 - Exam #4 - Final Exam Fall 2011 Name___________________________________________________ Total Open Response Problem 1:____________/25 Total Open Response Problem 2:____________/25 Total Open Response Problem 3:____________/25 Total Open Response Problem 4:____________/25 Total Points:__________________________/100 Percentage Score:______________________ % ***Answer all four problems! Each problem requires you to show all the steps in obtaining your answer. This includes, but is not limited to, defining all variables, showing/working the equations to be used, and including units with all values listed. All problems are worth up to 25 points each. Good Luck!!!! 1) A light spring with a spring constant of 90.0 N/m rests vertically on a table, as shown in illustration A. A 2.00 g balloon is filled with helium to a diameter of 1.0m and connected to the spring, causing the spring to stretch; as shown in illustration B. The magnitude of the force within the spring that pulls it back toward its unstretched position is equal to kDx (the Spring Force). Recall that the volume of a sphere is 4/3 p r3. How much does the spring stretch when the system is in equilibrium? A B 2) A drip-less candle (which means that the wax evaporates as the candle burns) is weighted slightly on the bottom so that it floats upright in a container of water as illustrated. Describe what happens as the candle burns. Be sure to label the free-body diagram to illustrate your point. 3) A copper wire (Y = 11 x 1010 Pa) of length 2.2 m and a steel wire (Y = 20 x 1010 Pa) of length 1.6 m, both of diameter 3.0 mm, are connected end-to-end. When stretched by a force, the total elongation is found to be 0.70 mm. Determine the force. 4) A liquid with a density of 1.65x103 kg/m3 flows through two horizontal sections of tubing joined end to end. as shown in the figure below. In the first section, the cross-sectional area is 10.0 cm2, the flow speed is 275 cm/s (VY), and the pressure is 1.20x105 Pa. In the second section, the cross-sectional area is 2.50 cm2. a) Calculate the flow speed in the smaller section (VU) b) Calculate the pressure in the smaller section. c) Imagine that some water squirts from tiny leaks at points Y and U. Which squirt shoots highest (or is there a tie)?