Physics 223 - Exam #3 - Final
December 11, 2009
Name______
Total Problems 1 - 6:______/60
Total Problem 7:______/25
Total Problem 8:______/25
Total Points:______/110
Percentage Score:______%
***Answer all of the questions (#1 through #9). All problems require you to show all the steps in obtaining the answer. This includes, but is not limited to, defining all variables, showing the equations to be used, and including units with all values listed. Problems 1 - 6 are worth up to10 points each. Problems 7 & 8 are worth up to 25 points each. Good Luck!!!!
1) A ball rolls around a circular wall (which is lying flat on a tabletop), as shown in the figure below. The wall ends at point X. When the ball gets to X, which path does the ball follow?
1. Path A
2. Path B
3. Path C
4. Path D
5. Path E
2) Two identical objects go around circles of identical diameter, but one object goes around the circle twice as fast as the other. The centripetal force required to keep the faster object on the circular path is
1. the same force required to keep the slower object on the path.
2. one fourth as much force as required to keep the slower object on the path.
3. half as much force as required to keep the lower object on the path.
4. twice as much force as required to keep the slower object on the path.
5. four times as much force as required to keep the slower object on the path.
3) Two objects, of masses 35 kg and 63 kg, are hung from the ends of a stick that is 70 cm long and has marks very 10 cm, as shown. If the mass of the stick is negligible, at which of the points indicated should a cord be attached if the stick is to remain horizontal when suspended from the cord?
1. A
2. B
3. C
4. D
5. E
6. F
7. G
4) Which will roll down an incline faster: a can of water or a can of ice? HINT: The water slides inside the can while the ice rolls along with the can.
1. the can of water
2. the can of ice
3. same speeds
4. It depends on the temperature.
5) Two balloons that have the same weight and volume are filled with equal amounts of helium. One is rigid and the other is free to expand as the pressure outside decreases. Which one will rise higher when released?
1. the rigid one
2. the expandable one
3. They will rise to the same level.
4. It's impossible to predict.
6) When an air bubble rises in water, what happens to its mass, volume, and density?
1. All three are conserved.
2. Mass doesn't change; volume decreases and density increases.
3. Mass doesn't change; volume increases and density decreases.
4. Volume doesn't change; mass and density decrease.
5. Volume doesn't change; mass and density increase.
6. Density doesn't change; mass and volume increase.
7. Density doesn't change; mass and volume decrease.
7) The two boards shown are in equilibrium, and are considered massless. The supporting string on the lower lever is attached a = 3m from the wall, and b = 2m from the other end. The slanted supporting string for the upper lever is attached c = 1m from the wall and d = 4m from the other end. The hanging mass is m = 2 kg. The upper, slanted string makes an angle of 30o with the board. What is the tension T in the slanted string?
9) A balloon filled with helium (ρ = 0.179 kg/m3) has an empty weight of 2.00 N and a volume of 0.500 m3. The balloon is surrounded by air (ρ = 1.29 kg/m3) and is secured to the ground by means of two strings, as shown below.
a) Completely label the free-body diagram.
b) Find the tension in the strings.