 
Summary: Physics 181.A Exam 3 Practice Fall 2008
Dr. S.G. Alexander Miami University
MULTIPLE CHOICE. Choose the one alternative that BEST completes the statement or answers the question, and mark
your scan sheet (only the scan sheet will be graded).
1) A potter's wheel, with rotational inertia 46 kg·m2, is spinning freely at 40.0 rpm. The potter drops a lump of
clay onto the wheel, where it sticks a distance 1.2 m from the rotational axis. If the subsequent angular speed of
the wheel and clay is 32 rpm, what is the mass of the clay?
A) 8.8 kg B) 5.4 kg C) 7.0 kg D) 8.0 kg
2) An irregularly shaped object 10 m long is placed with each end on a scale. If the scale on the right reads 74 N
and the scale on the left reads 93 N, how far from the left is the center of gravity?
A) 13 m B) 5.6 m C) 4.4 m D) 8.0 m
3) A solid, uniform sphere of mass 2.0 kg and radius 1.7 m rolls without slipping down an inclined plane of height
7.0 m. What is the angular velocity of the sphere at the bottom of the inclined plane?
A) 7.0 rad/s B) 5.8 rad/s C) 9.9 rad/s D) 11.0 rad/s
4) Use energy conservation to find the mass of planet where it is observed that a meteor is approaching in a
collision course. At 7514 km from the center of the planet, the meteor has a speed of 136.0 m/s and later at
2823 km a speed of 392.0 m/s.
A) 6.112 × 1028 kg B) 4.582 × 1020 kg C) 9.164 × 1027 kg D) 4.582 × 1021 kg
5) You are the science officer on a visit to a distant solar system. Prior to landing on a planet you measure its
diameter to be 1.8 × 107 m and its rotation period to be 22.3 hours. You have previously determined that the
