Download Lecture 14 Energy Dissipation Spring potential energy and more Lecture notes Physics in PDF only on Docsity! Department of Physics and Applied Physics PHYS.1410 Lecture 14 Danylov Lecture 14 Chapter 10 Energy Dissipation Spring potential energy Course website: http://faculty.uml.edu/Andriy_Danylov/Teaching/PhysicsI Physics I Energy dissipation Department of Physics and Applied Physics PHYS.1410 Lecture 14 Danylov Today we are going to discuss: Chapter 10: Energy Principle with Losses: Section 10.7-8 Chapter 11: Newton’s 2nd law (more general form): Section 11.1 Linear Momentum: Section 11.1 Impulse: Section 11.1 IN IN THIS CHAPTER, you will learn to use the concepts of impulse and momentum. ConcepTest Water Slide I A) Paul B) Kathleen C) both the same Paul and Kathleen start from rest at the same time on frictionless water slides with different shapes. At the bottom, whose velocity is greater? Conservation of Energy (for any of them): fi EE 2 2 1 mvmgh ghv 2 Ref. level U=0 ffii UKUK i f therefore: because they both start from the same height (h), they have the same velocity at the bottom. Department of Physics and Applied Physics PHYS.1410 Lecture 14 Danylov Spring Potential Energy What is the potential energy of a spring compressed from equilibrium by a distance x? kxFsp Uspring 1 2 kx2 Use a relation between potential energy and work: Potential energy of a spring Work done by a spring (from the previous class, Lecture 13) 22 2 ifsp xxkW Let’s combine them 22 2 )( ifif xxkUU From here you can see that the PE of a spring is Where x is a displacement from an equilibrium of a spring Department of Physics and Applied Physics PHYS.1410 Lecture 14 Danylov A 2 kg mass, with an initial velocity of 5 m/s, slides down the frictionless track shown below and into a spring with spring constant k=250 N/m. How far is the spring compressed? Brick/spring on a trackExample Department of Physics and Applied Physics PHYS.1410 Lecture 14 Danylov A block of mass m slides down a plane of length l and angle α. Find the speed of the block at the bottom of the incline plane assuming that it starts from rest and the coefficient of friction μ is constant. (Thermal energy is generated) mg α α kf Block sliding down Inclined PlaneExample Department of Physics and Applied Physics PHYS.1410 Lecture 14 Danylov Review mgyU Gravitational potential energy iiff UKUK E K U Total Mechanical Energy Conservation of Mechanical Energy 2 2 1 mvK Kinetic energy Uspring 1 2 kx2 Potential energy of a spring NCiiff WUKUK Without losses (no friction) With losses (with friction) ConcepTest Water Slide II Paul and Kathleen start from rest at the same time on frictionless water slides with different shapes. Who makes it to the bottom first? Even though they both have the same final velocity, Kathleen is at a lower height than Paul for most of her ride. Thus, she always has a larger velocity during her ride and therefore arrives earlier! A) Paul B) Kathleen C) both the same http://phys23p.sl.psu.edu/phys_anim/mech/ramped.avi Ref. level U=0
