1. Center of Mass

2. Curriculum Big Idea: All changes in rotational motion are due to torques. Concept: Torque is the rotational analogue of force for translational motion PA Standard: 3.2.12.B1 “Analyze the principles of rotational motion to solve problems relating to angular momentum and torque.” This lesson on center of mass will help you lay the foundation for this concept.

3. Today’s Agenda Opener: Answer the “What Do You Think?” Questions in the Center of Mass packet. For You To Do – Find the center of mass of 2-dimensional shapes. Center of Mass Demonstrations Center of Mass for Projectiles VideoVideo Center of Mass Physics Words Center of Mass Physics to Go Closure Questions Take Home Assignment: Newton’s Laws Individual Benchmark Quiz tomorrow

4. Physics Words center of mass: point at the center of an object’s mass distribution, where all of its mass can be considered to be concentrated. For everyday conditions, it is the same as the center of gravity. torque: the rotational analog of force; the product of the force and the lever arm (measured in N-meters). Torque tends to produce rotational acceleration. stable equilibrium: the state of an object balanced so that any small displacement or rotation raises its center of gravity.

5. Closure Questions 1. Can an object’s center of mass be located outside of the object? What are some examples? 2. Where does the center of mass have to be located in order for an object to fall over? 3. What is the pathway for the center of mass for all projectiles?