Physics 321 -- Spring 2006

Homework #2, due Wednesday Jan. 25 at beginning of class

1.         [4pts] Marion & Thornton, problem 2-29.
(An “8% grade” means that the vertical distance is 0.08 when the horizontal distance is 1.0 .)

2.         [4pts] Marion & Thornton, problem 2-41.
It is possible to do this problem in your head and just write down the answers.  If you do that, then check your answers to parts (c) and (d) in the following way.  Assume that the woman exerts a constant force F on the ball during a time T. Express F in terms of m, v, and T using Newton’s 2nd Law, then calculate the work done by the force F and check that it matches your result to part (c).  For part (d), notice that the horizontal force the train exerts on the woman while she throws the ball is the same F as above.  From that F, calculate the work done by the train on the woman while she throws the ball, and check that it equals your answer to part (d).  Hint: How far does the woman move with respect to the ground while she is throwing the ball?

3.         [4pts] Marion & Thornton, problem 2-40.
“Tangential acceleration” is the component of the acceleration in the direction of the velocity.
“Normal acceleration” is the component of acceleration perpendicular to the velocity.

4.         [4pts] Marion & Thornton, problem 2-47. (The constants "a" and "alpha" are supposed to be the same.)

            After doing the problem as stated, answer the following questions assuming the particle has a total energy of 3 Joules and a mass of 0.2 kg: 

(a) What are the limits of its motion in the potential?

(b) What is its speed when it passes the point x=3 m?

5.         [4pts] Marion & Thornton, problem 2-22.

(Last updated 1/18/2006.)