Warm-up 8 Question

The following question is about problem-solving You do not have to do any actual calculations. (This problem is taken from Physics Today, September 1991.)

Consider the following problem:

1. A 1-kg stick of length 1m is placed on a frictionless horizontal surface and is free to rotate about a vertical axle through one end. A 50-g lump of clay is attached 80 cm from the pivot. The pivot+clay is rotating with an angular velocity of 3 rad/s. What is the net force between the stick and the clay?

Which of the following problems, A, or B, would you solve most like problem 1? Explain your answer briefly but clearly.

1. A stick of length 1.5m and mass 0.2 kg is on a frictionless horizontal surface and is rotating about a pivot at one end with an angular velocity of 5 rad/s. A 35-g lump of clay drops vertically onto the stick at its midpoint. If the clay remains attached to the stick, find the final angular velocity of the stick-clay system.
2. A 60-kg block is held in place on a frictionless inclined plane of angle 25 degrees. The block is attached to a hanging mass by a light string over a frictionless pulley. Find the value of the hanging mass so that the block does not move when released.

Remember, you do not have to solve the problem, just describe in words which problem (A or B) you would solve most like problem 1. Explain your reasoning briefly.

Table of Contents

• 1 A: They are both Chapter 8 Problems.
• 2 A: B uses vectors.
• 3 B.