Physics 321 -- Spring 2003

Homework #3, due Wednesday Jan. 29

1. (3) Marion & Thornton: problem 9-4.

2. (3) Marion & Thornton, problem 9-8.

3. (4) Marion & Thornton, problem 9-9.

Hint: First calculate the projectile’s velocity and kinetic energy at the moment just before it explodes. Then use conservation laws and the information given to calculate all the velocities immediately after the explosion. Ignore the last question, “What is the ratio …”

4. (2) Marion & Thornton, problem 9-12.

In part (b), specify in which frame of reference you are calculating the velocity of the tank.

5. (2) Marion & Thornton, problem 9-21.

6. (3) Marion & Thornton, problem 9-22.

At first glance, you may think that you need to use conservation of angular momentum (which we haven’t yet discussed) to do this problem. That is not true, however. The angular momentum of the mass is not conserved, because the tension of the string produces a torque on the particle. Fortunately, some other quantity is conserved. What is it? Hint: The force on the particle is always perpendicular to its velocity.

7. (3) Marion & Thornton, problem 9-28.

8. (2) Marion & Thornton, problem 9-35.

9. (3) Marion & Thornton, problem 2-44.