Week 13 (Apr. 8 - 12)

Read: Centripetal Force and Acceleration (ASGv2 Chap. 24) and Newton's Rules of Reasoning (ASGv2 Chap. 25).

Key topics: rotational motion, centripetal force, centripetal acceleration, principle of parsimony, principle of induction, philosophy of nature.

PHY 201 Lecture: torque, rotational inertia, and angular motion.
Quiz: None. No class on Monday since I will be in Ohio viewing the solar eclipse!


  1. PHY 201: Kinetic Energy (Ex. 23.5)
  2. Inferring force laws (Ex. 24.1)
  3. Whirling beads (Ex. 24.2)
  4. Race track: A 2000 kg race car rounds a curve at 150 mph. The radius of curvature of the track is 100 meters. What is the minimum coefficient of friction between the tires and the road so that the car does not slide?
  5. David's sling: King David, facing Goliath, swings a stone in the pouch of a sling above his head. The trajectory of the stone is in a circle whose plane is parallel to the ground. The sling is of length L = 1 meter; the stone is of mass m = 200 grams. The rotation rate is twice per second. Ignore gravity and drag (let's focus on the circular motion). (a) Draw a free body diagram for the stone at a particular instant. (b) What is the speed of the stone? Is it accelerating? If so, in which direction? (c) What is the tension in the string? What would happen if the string snapped?
  6. Rules of Reasoning Essay (Ex. 25.1)

Lab: Collisions Laboratory (Ex. 22.7).

Collisions Laboratory:
Professor Schindler and I carried out this lab and prepared some instructional videos that will help you with this week's collision lab; here they are!

Chapter 24: In chapter 24, Newton explains how the motion of an orbiting object reveals the nature of the forces acting upon it.

Chapter 25: Here is a video about Newton's rules of reasoning.

Physics 1