PHYS 241 Recitation Kevin Ralphs Week 1

Overview Introduction Preliminaries Tips for Studying Physics Working with Vectors Coulomb’s Law Principle of Superposition Electric Fields

Introduction I’m Kevin Ralphs, your TA – – Web site: web.ics.purdue.edu/~kralphsweb.ics.purdue.edu/~kralphs – Office: PHYS 137 – Office Hours: By appointment

Preliminaries Recitations will largely focus on a conceptual approach to the material Memorization of equations and constants will not help you on the exam Understanding the concepts often allows you to almost instantly answer a question

Tips for Studying Physics Universal vs Situational Formulae – Very few of the formulas you will encounter are always applicable – It is imperative to know the situation for which a formula is valid Limited Amount of Symbols – We will use a mix of Latin and Greek letters as symbols – Unfortunately we will have more than 49 different quantities which means we will sometimes reuse symbols – Just because 2 formulae have the same symbols does not mean they can be used together Identify the Type of Problem – Particle Motion – Raw Calculation – Before and After

Working with Vectors Vectors are commonly defined as having direction and magnitude, but this is false – This is a geometric description, but vectors are defined by their algebraic properties – They can be given a notion of direction and magnitude, however In reality, vectors are members of a set called a vector space that has two binary operations, addition and scalar multiplication, that combine linearly

Working with Vectors

Coulomb’s Law What does it tell me? – It tells you the force between two charged particles Why do I care? – Forces describe the acceleration a body undergoes – The actual path the body takes in time can be found from the acceleration in two ways 1.Use integration to get the particle’s velocity as a function of time, then integrate again to gets its position 2.Kinematic equations (the result when method 1. is applied in the case of constant acceleration)

Coulomb’s Law

Principle of Superposition

Electric Field Universal

Electric Field Situational

Electric Field