Reading:

Cutnell and Johnson, Chapter 9.

Problems for Review:

Reviewing these problems gives you good exposure to this week's main topics, in practice. All solutions are posted on our website |http://www.cc.emory.edu/PHYSICS/Faculty/Benson/141/review.html|. Quantitative solutions are also in the Student Study Guide.

Conceptual:

MCAT review problem 11 (on website).

Quantitative:

Chapter 9, problems 1,9,13,23,29,39,49,57,65.

Problems to Hand In:

Conceptual:

Use the following to answer questions 1 -- 6:

A laboratory balance is constructed as shown:

The rod has a mass of 0.5 kg. The counterweight has a mass of 0.01 kg. With nothing on the pan, the rod is balanced at x = 1 cm.

1. What is the mass of the pan?
   1. 0.1 kg
   2. 0.5 kg
   3. 1.0 kg
   4. 5.0 kg
   
   
2. In general, when calculating the mass of the pan, neglecting the mass of the rod
   1. is possible, if the fulcrum is placed at the center of mass of the whole balance.
   2. is possible, if the center of mass of the rod is the pivot point.
   3. is not possible under any circumstances.
   4. is possible, if the chemical mass is larger than the mass of the rod.
   
   
3. Based on the above picture, when calculating the mass of the pan, the fulcrum
   1. exerts no force on the rod, so the fulcrum can be ignored.
   2. exerts a force on the rod, but no torque.
   3. exerts a torque on the rod, but no force.
   4. exerts a torque and a force on the rod.
   
   
4. If an amount of chemical is now added to the pan, in order to balance the rod, what happens to x?
   1. It increases.
   2. It decreases.
   3. It remains the same.
   4. Whether x increases or decreases depends on the amount of chemical added to the pan.
   
   
5. If there is no chemical in the pan, and the counterweight is now moved from 1 cm to 5 cm
   1. the rod is no longer in translational or rotational equilibrium.
   2. the rod is in translational equilibrium, but not in rotational equilibrium.
   3. the rod is in rotational equilibrium, but not in translational equilibrium.
   4. the rod is still in both translational and rotational equilibrium.
   
   
6. If the net force and net torque on an object are both zero, what can you conclude?
   1. The object will necessarily be at rest.
   2. The object may be in motion.
   3. The object is necessarily in circular motion.
   4. Net force and net torque cannot simultaneously be zero.
   
   

Quantitative I:

Complete these end-of-chapter problems (not questions!) from your textbook, submitting only your final circled choice for an answer.

Chapter 9.

2.

12.

14.

22.

32.

44.

50.

56.

Quantitative II:

Chapter 9, problems 31, 41.

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