Conservation of Energy

Slides:



Advertisements
Similar presentations
Practice Problem #1 A weightlifter bench presses 80kg (approx. 175lbs.) 0.75m straight up. a. How much work does she do, assuming constant velocity, in.
Advertisements

ConcepTest 6.5a Kinetic Energy I
ConcepTest Clicker Questions
Reading Quiz A cannonball is dropped from a tower. As it falls,
WORK AND ENERGY. The work done by a force is the product of the magnitude of the force and the distance moved in the direction of the force Recall the.
AP Physics C I.C Work, Energy and Power. Amazingly, energy was not incorporated into physics until more than 100 years after Newton.
An object is released from rest on a planet that
E W Work and Energy Work Done By a Constant Force Work is defined as the product of the constant force and the distance through which the point of application.
Chapter 9 Potential Energy & Conservation of Energy
Energy Physics 11. Types of Energy  Name as many different types of energy as you can. Think of an example to go with each.
Aim: How can we solve problems dealing with the Law of Conservation of Energy? HW #10 due tomorrow Do Now: A 10 kg object free falls off the top of a 100.
Work, Energy and Power. Work = Force component x displacement Work = F x x When the displacement is perpendicular to the force, no work is done. When.
Adv Physics Chapter 5 Sections 3 & 4.
Phy100: More on Energy conservation Mechanical energy (review); Goals: Work done by external forces; Understand conservation law for isolated systems.
Physics 151: Lecture 15, Pg 1 Today’s Topics l Potential Energy, Ch. 8-1 l Conservative Forces, Ch. 8-2 l Conservation of mechanical energy Ch.8-4.
Work, power and energy(2)
Everyday Forces Chapter 4 Section 4.
Chapter 5 Work and Energy
Chapter 6 Work and Energy. 6.1 Work Done by a Constant Force.
CONSERVATION OF MECHANICAL ENERGY
WORK In order for work to be done, three things are necessary:
WORK In order for work to be done, three things are necessary:
Bellringer 10/25 A 95 kg clock initially at rest on a horizontal floor requires a 650 N horizontal force to set it in motion. After the clock is in motion,
Copyright © 2010 Pearson Education, Inc. Chapter 7 Work and Kinetic Energy.
Work done by individual forces
Work and Energy. Work a force that causes a displacement of an object does work on the object W = Fdnewtons times meters (N·m) or joules (J)
Kulwant Work-Energy Principle Conservation of Mechanical Energy Work done = Change in K.E. + Change in PE A rough slope is inclined at tan -1 ( ¾ ) to.
Conservative Forces: The forces is conservative if the work done by it on a particle that moves between two points depends only on these points and not.
Physics. Session Work, Power and Energy - 3 Session Objectives.
Chapter 6 Work and Energy. Force,displacement  WORK.
Work and Energy.
Aim: How can we explain the Law of Conservation of Energy? Do Now: Homework Review.
5.3 The Conservation of Mechanical Energy THE PRINCIPLE OF CONSERVATION OF ENERGY The term conserved means constant.
Fall Semester Review: Physics Situation 1: Air resistance is ignored. A person is standing on a bridge that is 150 m above a river. a. If a stone with.
Lecture 11: Potential Energy & Energy Conservation.
WORK, ENERGY AND POWER WHY ARE WE WORKING SO HARD?
Work - Work is calculated by multiplying the force applied by the distance the object moves while the force is being applied. W = Fs.
Motion, Forces and Energy Lecture 7: Potential Energy & Conservation The name potential energy implies that the object in question has the capability of.
Chapter-6 Work and Energy Work Done by a Constant Force Work is done when a force F pushes a car through a displacement s. Work = Force X Displacement.
Work and Energy x Work and Energy 06.
Objectives: The students will be able to: Solve problems using the law of conservation of energy. Solve problems using the law of conservation of energy.
5-3: Conservation of Energy Objectives: Identify situations in which conservation of mechanical energy is valid Recognize the forms that conserved energy.
Wednesday June 15, PHYS , Summer I 2005 Dr. Andrew Brandt PHYS 1443 – Section 001 Lecture #9 Wednesday June 15, 2005 Dr. Andrew Brandt Lightning.
Chapter 5.2. What do you think? What is meant when scientists say a quantity is conserved? Describe examples of quantities that are conserved. Are they.
Examples: Mechanical Energy Conservation
Work Kinetic Energy Work – Energy Theorem Gravitational Potential Energy Mechanical Energy Conservation of Energy Work Kinetic Energy Work – Energy Theorem.
Section 6-3 Gravitational Potential Energy. Warm-Up #1 A sailboat is moving at a constant velocity. Is work being done by a net external force acting.
Physics 218: Mechanics Instructor: Dr. Tatiana Erukhimova Lectures 16, 17, 18.
PHY 101: Lecture Work Done by a Constant Force
EnergyDefinitions 1 Different kinds of energy Kinetic energy Kinetic energy is motion energy. The faster it moves the more kinetic energy it possesses.
Energy Physics 11. Think about… 5 min 1) Why is energy important? 2) Where does energy come from? Where does it go? 3) How do we capture energy? 4)How.
Work-Energy Relationship Already understand that lifting an object will increase the object’s gravitational potential energy. W=ΔPE= mgΔh No friction.
Unit 7: Work, Power, and Mechanical Energy.
Work, Energy & Power.
Work -   Work is calculated by multiplying the force applied by the distance the object moves while the force is being applied.   W = Fs.
Different kinds of energy
Work Done by a Constant Force
Energy Physics 11
Conservation of Energy
Energy IN = Energy OUT Means ALL Energy
Energy IN = Energy OUT Means ALL Energy
Work Yes you out there !.
Power.
Energy Mechanical.
Work, Energy, Power.
Forces In the Rough.
Forces The unedited story.
Work and Energy Practice
Presentation transcript:

Conservation of Energy

Facts Conservation of energy When gravity is the only force which does work on a body, mechanical energy is conserved. PEstart + KEstart = PEend + KEend This is also true when an external force is applied PEstart + KEstart + Win = PEend + KEend+ Wout

Examples A toolbox of mass 3 kg, is knocked off a table which is 0.3 m above the ground. Using conservation of energy, calculate the vertical speed with which the toolbox lands on the ground. 3g 0.3 m Zero PE level As the toolbox falls the initial PE at the start is converted into KE at the end PEstart = KEend mgh = ½mv² 3 x 9.8 x 0.3 = ½ x 3 x v² v² = 5.88 v = 2.42 ms-1

There is an external force being applied so A 10 kg mass is pulled along a rough horizontal surface by a horizontal force of magnitude 100N. The mass is initially at rest and it is pulled by the force for a distance of 10m. The coefficient of friction between the mass and the surface is 0.6. Use the work – energy principle to find the final speed of the mass. 0 ms-1 v ms-1 R Fr 100 N  = 0.6 10g 10 m There is an external force being applied so PEstart + KEstart + Win = PEend + KEend+ Wout 0 + 0 + Fs = 0 + ½mv² + Frs 100 x 10 = ½ x 10gv² + Frs 1000 = 5gv² + 10 x 6g 1000 – 60g = 5gv² v² = 412 v = 9.08 ms-1 (3 s.f.) We need to find friction Fr= R = 0.6 x 10g = 6g

PEstart + KEstart + Win = PEend + KEend+ Wout A female athlete of mass 65kg runs up a slope inclined a 5º to the horizontal. Her speed at the bottom of the slope is 4 ms-1 and her speed decreases to 3 ms-1 at the top of the slope. The slope is 120 m long and the resistances to motion can be assumed constant at 40 N. Determine the constant force she must exert to get to the top of the slope. 3 ms-1 R F 120 m 40 N 4 ms-1 65g R h = 120sin 5º F 40 N 5º zero PE level 65g The athlete starts with KE and work and ends with KE, PE and resistances PEstart + KEstart + Win = PEend + KEend+ Wout 0 + (½ x 65gx 4²) + 120F = (65g x 120sin 5º) + (½ x 65gx 3²) + (40 x 120) 520 + 120F = 6662.2 + 292.5 + 4800 120F = 11234.7 F = 93.6 N (3 s.f.)

Your turn now Blue book pg 261, 262 Mechanics 2 exercise 4B page 86 all the questions

Feedback: Privacy Policy Feedback
Do Not Sell My Personal Information
About project: SlidePlayer Terms of Service

© 2025 SlidePlayer.com. Inc. All rights reserved.