EF 152 Physics for Engineers II

Transcription

1 EF 152 Physics for Engineers II Prof. Will Schleter Prof. Amy Biegalski Physics I Review: Physics II Preview: Vectors, Ratios, Estimation, 1D, 2D Motion Projectile Motion, Relative Motion, Newton s Laws, Friction Work, Energy, Linear Momentum, Collisions Center of Mass, Rotations, Angular Momentum, Torque Module 1 Statics, Materials, Gravitation, Fluids Module 4 Electrostatics, Resistors, DC Circuits, Capacitors, Magnetism Module 3 Temperature, Ideal Gases, Heat Flow, Heat Engines, Refrigerators Module 2 Simple Harmonic Motion, Pendulums, Waves, Sound, Light Development as an Engineer Examine engineering principles and design issues, Develop teamwork & time management skills, Enhance oral and written communication and presentation skills, Analyze and interpret engineering data to draw reasonable conclusions. EF 152 Lecture EF 152 Lecture EF 152 Lecture Configuration Mondays and Wednesdays EF 152 Lab Tuesdays and Thursdays Labs are for: Hands-on activities related to lecture material Problem solving practice Homework help Team project work Room and table assignments 4 sections meet at each time slot Team assignment based on CatMe New room and table assignment based on team EF 152 Lecture EF 152 Lecture 1-1 4

2 Details Everything is on the web site Statics GTAs will review most of this in the first lab Syllabus / Calendar Instructors / GTAs / Availability Grading Lecture / Pre-lecture / Lecture Videos / Clickers Lab / Attendance Homework / Portfolio Study Room / Discussion Board Exams Procedures / Forms Newton s Second Law If not accelerating, 0 Torques/Moments τ EF 152 Lecture EF 152 Lecture Satellites Fluid Flow Chemical Processing Plant Normal acceleration Sum forces Bernoulli s Equation 1 2 +h h + Conservation of Energy 1 2 +h + +h + EF 152 Lecture EF 152 Lecture 1-1 8

3 Simple Harmonic Motion Physical Pendulum Often used to find Mass Moment of Inertia Mass Moment of Inertia % % &' +! Sound Industrial Equipment Vibration Newton s Second Law Springs Kinematics!"!#!!#! "!# EF 152 Lecture Pendulum powered pump for developing countries EF 152 Lecture Doppler First Law of Thermodynamics Doppler Radar Doppler Ultrasound Relative Motion (/* +/* + (/+ First Law -./ Radar Gun Doppler Spectroscopy EF 152 Lecture Work-Energy 0 EF 152 Lecture

4 Electrostatics DC Circuits Electrostatic Painting Electrostatic Dust Filter Organ Transport keeping a heart beating while being transported to a transplant patient Kirchoff s Voltage Law Potential 34#56# :h5 Laser Printers EF 152 Lecture EF 152 Lecture Electric and Magnetic Fields Electric Generator Cross Product ; < >; >;? < 4A Electric Cars Carbon Nanotubes self-assemble under presence of electric field from a Tesla Coil EF 152 Lecture Module 1 Learning Objectives Statics Isolate bodies and draw accurate free body diagrams and kinetic diagrams. Identify and represent forces acting between a body and other bodies and attached cables and connections (supports). Recognize the tendency of a force to create rotation as a moment and determine the magnitude and direction of the moment of a force by identifying the moment arm. Utilize free body diagrams and equations of static equilibrium based on Newton s Second Law to analyze forces acting on a body. Utilize free body diagrams and equilibrium equations to perform stability (overturning) calculations. Materials Define the terms stress, strain, linear elastic, deformation, and elastic modulus. Utilize Hooke s Law to calculate axial stress and deformation in linear elastic materials. Understand and apply the concept of a Factor of Safety to engineering designs. Investigate engineering materials with novel properties. Gravitation Understand and apply Newton s Law of Universal Gravitation. Use Conservation of Energy, velocity and acceleration equations to analyze orbiting bodies. Understand and apply Kepler s Laws to elliptical orbits. Fluids Define properties of fluids, flow rate, absolute and gage pressure. Apply Archimedes principle to problems related to the buoyant forces acting on objects immersed or floating in a fluid. Apply the Continuity Equation and Bernoulli s equation to analyze fluid pressures. EF 152 Understand and apply Stokes Law and Poiseuille s Equation 16

5 Statics, Free Body Diagrams FBD - Intuition Review: Newton s 2 nd Law F net ma Free Body Diagram (FBD) FBD KD Schematic Representation A B Diagram of free from surroundings and showing all that act on body Butch Jones is standing on a diving board. Which is true about the forces exerted on the diving board? 1. F A is down, F B is up, F B > F A 2. F A is down, F B is up, F A > F B 3. Both forces are up, F A > F B 4. Both forces are up, F B > F A Identify Draw Define a system EF 152 Lecture EF 152 Lecture Static Equilibrium F ma If the resultant of all the forces is zero, then the body is not If the body is not accelerating, the resultant of all the forces on the body is τ Iα Also need to consider and acceleration In statics, torques are called If the resultant of all the moments is zero, then the body does not have If the body does not have angular acceleration, the resultant of all the on the body is zero EF 152 Lecture Equations of Static Equilibrium F 0 M 0 Two Dimensions 0 Fy 0 M 0 No net moment about any point Therefore can calculate moments about Good choice leads to considerable simplification Moment about point where force is, or any point along of force, is zero. F A Force does not create a moment about A. Recall: The moment of a force is a measure of its tendency to rotate an object about some point Force times perpendicular distance EF 152 Lecture F x B F z A Force does not create a moment about A or B.

6 Supports Example: Beam Given: Uniform beam of weight 5 kn. Pin 3 kn 10 kn Roller Roller Support Fixed Support 0.9m 2.4m 0.7m Pin Support Required: Reaction forces Cables: only tension along axis of cable EF 152 Lecture Which end will support the most force? At what point should we sum moments about? EF 152 Lecture Beam: FBD F xpin F ypin 3 kn 5 kn 10 kn 0.9m 2.4m 0.7m 2.0m F roller Example: Hanging Sign A 12 lb beam is used to support a 32 lb sign. The beam is attached to the wall with a hinge, and also supported by a cable. Determine the magnitude of the force in the hinge pin and the force in the cable ft y X EF ft EF 152 Lecture EF 152 Lecture