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General Physics 2, Spring '11

Homework 4

1. Pick one of the Questions for Thought and Discussion (not the Projects!) to contemplate and answer. (Make sure it isn't one that we talked about in class already.)

2. Work through the falling yo-yo problem from Wednesday's class: the yo-yo has radius R, mass M, and moment of inertia I, and is unwinding downward; your job is to find its acceleration. We did this in class already using energy conservation. So you should do it using torque and angular momentum. You may choose the origin of your coordinate system anywhere you want; just be explicit about what you're doing. (There are two places you might choose that will make this very similar to the worked example in the text; if you're feeling ambitious/curious you might try putting it somewhere else and showing that you still get the right answer out at the end.)

3. Project 4.5. Hint: if the platform/board is going to be in equilibrium, not only must the net force vanish, but the net torque must also vanish.

4. Several of the Projects for this chapter (e.g., 4.3, 4.4, 4.11) presuppose that you know calculus. If you do know calculus, pick one of those to work out. Follow the method in the examples in the text! If you don't know calculus, do Project 4.6 instead.

Homework 4

1. Pick one of the Questions for Thought and Discussion (not the Projects!) to contemplate and answer. (Make sure it isn't one that we talked about in class already.)

2. Work through the falling yo-yo problem from Wednesday's class: the yo-yo has radius R, mass M, and moment of inertia I, and is unwinding downward; your job is to find its acceleration. We did this in class already using energy conservation. So you should do it using torque and angular momentum. You may choose the origin of your coordinate system anywhere you want; just be explicit about what you're doing. (There are two places you might choose that will make this very similar to the worked example in the text; if you're feeling ambitious/curious you might try putting it somewhere else and showing that you still get the right answer out at the end.)

3. Project 4.5. Hint: if the platform/board is going to be in equilibrium, not only must the net force vanish, but the net torque must also vanish.

4. Several of the Projects for this chapter (e.g., 4.3, 4.4, 4.11) presuppose that you know calculus. If you do know calculus, pick one of those to work out. Follow the method in the examples in the text! If you don't know calculus, do Project 4.6 instead.

Last modified: Monday, December 19, 2011, 9:18 AM