Energy 1. Work 2. Kinetic Energy 3. Work-Energy Principle 4. Friction 5. Potential Energy 6. Conservation of Energy ©2013 Robert Chuckrow.

Slides:



Advertisements
Similar presentations
Conservation of Energy
Advertisements

Explaining motion P4. Big picture How forces arise How forces arise Friction and normal reaction Friction and normal reaction Adding forces Adding forces.
ConcepTest 6.5a Kinetic Energy I
ConcepTest Clicker Questions
© 2005 Pearson Prentice Hall This work is protected by United States copyright laws and is provided solely for the use of instructors in teaching their.
Reading Quiz A cannonball is dropped from a tower. As it falls,
An object is released from rest on a planet that
Work, Energy & Power Honors Physics. There are many different TYPES of Energy. Energy is expressed in JOULES (J) 4.19 J = 1 calorie Energy can be expressed.
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.
Work, Energy, And Power m Honors Physics Lecture Notes.
Phy100: More on Energy conservation Mechanical energy (review); Goals: Work done by external forces; Understand conservation law for isolated systems.
Newton’s Laws of Motion three laws of motion: fundamental laws of mechanics describe the motion of all macroscopic objects (i.e., everyday size objects)
 For circular motion: Centripetal force = gravitational force (F C = F G ) Recap: Orbital Velocity M = planet’s mass m = satellite’s mass r MG v or 
The Work Energy Principle Part 4 By Heather Britton.
Ch 8 Energy Notes Concept Summary Batesville High School Physics
Chapter 6 Work & Energy.
Chapter 12: Energy & Work Unit Integrated Science I.
Work and Energy. Definitions Work – the product of force and the component of displacement in the direction of the force. - work is a scalar quantity.
Dr. Steve Peterson Physics 1025F Mechanics ENERGY Dr. Steve Peterson
Energy the ability (capacity) to do work Energy comes in many forms: mechanical, electrical, magnetic, solar, thermal, chemical, etc... thermal, chemical,
Work, Energy & Power AP Physics B. There are many different TYPES of Energy. Energy is expressed in JOULES (J) 4.19 J = 1 calorie Energy can be expressed.
Work, Power, Energy Work.
Physics Chapter 11 Energy.
Unit 5 Mechanical Principles and Applications
The Work Energy Theorem Up to this point we have learned Kinematics and Newton's Laws. Let 's see what happens when we apply BOTH to our new formula for.
Work and Energy Conservative/Non-conservative Forces.
Mechanics Work and Energy Chapter 6 Work  What is “work”?  Work is done when a force moves an object some distance  The force (or a component of the.
Energy m m Physics 2053 Lecture Notes Energy.
Work IN, Work OUT The Work/Energy Principle. Kinetic Energy KE depends on mass and velocity Work done on an object will change KE.
Energy, Work & Power: Types of Energy The following are some examples of types of energy: Internal energy Gravitational potential energy = mgh Kinetic.
Work, Power and Energy. Basic Terms - Work Work (in physics) is defined as a force acting over a distance. W = F x d Scalar Quantity: Units: Making the.
Chapter 6 Work and Energy. Units of Chapter 6 Work Done by a Constant Force Kinetic Energy, and the Work-Energy Principle Potential Energy Conservative.
Work and Energy.
Work and Energy. Work Done by a Constant Force The work done by a constant force is defined as the distance moved multiplied by the component of the force.
Energy. Analyzing the motion of an object can often get to be very complicated and tedious – requiring detailed knowledge of the path, frictional forces,
Work and Energy.
Conservation of Energy IT’S THE LAW. Lifting a Ball When you lift a ball to a certain height you do work on it. When you lift a ball to a certain height.
Ch. 6, Work & Energy, Continued. Summary So Far Work-Energy Theorem: W net = (½)m(v 2 ) 2 - (½)m(v 1 ) 2   KE Total work done by ALL forces! Kinetic.
Work done by a constant force Kinetic Energy Gravitational Potential Energy Simple Machines WORK AND ENERGY.
WORK A force that causes a displacement of an object does work on the object. W = F d Work is done –if the object the work is done on moves due to the.
Conservation of Mechanical Energy Mechanical Energy – The sum of Potential and Kinetic Energies ME=PE+KE The conservation of mechanical energy states that.
Energy and its Conservation
Wednesday June 15, PHYS , Summer I 2005 Dr. Andrew Brandt PHYS 1443 – Section 001 Lecture #9 Wednesday June 15, 2005 Dr. Andrew Brandt Lightning.
Momentum and Energy. Momentum is Mass x Velocity: Each Plane has Mass m Each Plane has Velocity v Each Plane has Momentum  p = mv.
WORK, ENERGY & POWER AP Physics 1. There are many different TYPES of Energy. Energy is expressed in JOULES (J) 4.19 J = 1 calorie Energy can be expressed.
Work, Energy & Power AP Physics B. There are many different TYPES of Energy. Energy is expressed in JOULES (J) 4.19 J = 1 calorie Energy can be expressed.
Work, Power, Energy and Motion Work, Power, Energy and Motion moving train cars moving electrons nuclear forces chemical forces gravitational force Electrical.
Pre-AP Physics.  Energy is expressed in JOULES (J)  4.19 J = 1 calorie  Energy can be expressed more specifically by using the term WORK(W) Work =
Work, Power & Energy How do they relate? (Stone, Ebener, Watkins)
Work, Energy & Power AP Physics B. There are many different TYPES of Energy. Energy is expressed in JOULES (J) 4.19 J = 1 calorie Energy can be expressed.
Everyone grab a small whiteboard and a dry erase marker.
Conservation of Energy IT’S THE LAW. Lifting a Ball When you lift a ball to a certain height you do work on it. When you lift a ball to a certain height.
 Work  Energy  Kinetic Energy  Potential Energy  Mechanical Energy  Conservation of Mechanical Energy.
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.
UB, Phy101: Chapter 6, Pg 1 Physics 101: Chapter 6 Work and Kinetic Energy l New stuff: Chapter 6, sections
1 Energy conservation of energy work, energy, and power machines & efficiency Homework: RQ: 3, 4, 5,10, 12, 13, 15, 18, 30. Ex: 23, 26, 28, 37, 49, 62.
Work Done by a Constant Force The work done by a constant force is defined as the distance moved multiplied by the component of the force in the direction.
Energy Notes Energy is one of the most important concepts in science. An object has energy if it can produce a change in itself or in its surroundings.
Review velocity is (change in position)/time elapsed acceleration is (change in velocity/time elapsed Changes can be in magnitude or in direction or both.
EnergyDefinitions 1 Different kinds of energy Kinetic energy Kinetic energy is motion energy. The faster it moves the more kinetic energy it possesses.
Potential Energy (PE or U) Definition: The energy that an object has by virtue of its position relative to the surface of the earth. PE = mgh Compare the.
PHY 102: Lecture 4A 4.1 Work/Energy Review 4.2 Electric Potential Energy.
Work, Power & Energy.
Different kinds of energy
Energy IN = Energy OUT Means ALL Energy
Energy Conversion and Conservation
Energy comes in many forms: mechanical, electrical , magnetic, solar,
Energy IN = Energy OUT Means ALL Energy
Physics: Work and Energy
Presentation transcript:

Energy 1. Work 2. Kinetic Energy 3. Work-Energy Principle 4. Friction 5. Potential Energy 6. Conservation of Energy ©2013 Robert Chuckrow

1. Work Work W is defined as the part of the force in the direction of the motion multiplied by the distance moved: W = F // x d. Note: The part of the force perpendicular to the motion does no work. Question: Can work ever be negative?

Answer to Q. 1, and a new Question Answer: Yes, work done by a force is negative if the direction of the force doing the work is opposite to that of the motion (slowing the object down). Question 2: Can a force exerted on a moving object ever do zero work?

Answer to Q. 2, and a new Question Answer: Yes, a force exerted on a moving object can do zero work if it is perpendicular to the motion. Question 3: Are there other cases in which a force exerted on an object does zero work?

Answer to Question 3 Answer: Yes, a force exerted on a stationary object does zero work. Summary: (a) The work done by a force is negative when the direction of the force is opposite to that of the motion. (b) A force does zero work if it is perpendicular to the motion. (c) A force does zero work if it is exerted on a stationary object.

2. Kinetic Energy The Kinetic Energy (KE) of a mass m, moving with speed v is defined: KE  mv  . Question: By what factor does the KE of an object change if: (a) its mass is doubled, but its velocity remains the same? (b) its velocity is doubled, but its mass remains the same?

Answer Recall, KE  mv  . (a) If an object’s mass is doubled, keeping its velocity the same, its KE doubles. (b) If an object’s velocity is doubled, keeping its mass the same, its KE quadruples.

3. Work-Energy Principle The Work-Energy Principle: The work done by all forces on an object equals its change in kinetic energy. Work total = Change in KE Think: Check the consistency of the above principle with Newton’s first and second laws.

4. Friction When an object moves on a “rough” surface, the direction of the force of friction is always opposite to that of the motion. Consequently, friction does negative work. When friction causes a moving object to slow down, the negative work done by friction reduces that object’s KE. It might seem that the energy of the moving object is thereby totally lost, but actually, it becomes microscopic KE; namely, the random jiggling of molecules of the object and surface increases. That is, their thermal energy increases (their temperature rises). Because it is random, thermal energy is very hard to retrieve, so as far as mechanical energy is concerned, it is lost.

5. Potential Energy Lift a mass m through a height h. The work I do will be mg x h. Where did the energy go? Answer: It is potentially available because, if I drop the mass, gravity will do mg x h of work on the mass—the same amount of work that it took to lift it. Therefore, by my lifting the mass, the energy I expended was not lost but went into potential energy = mgh. Note: The word potential comes from the word potent (having power), so potential means having power that has not yet been brought into being.

6. Conservation of Energy We also say that during its way down, the falling mass lost potential energy (PE), which was converted into kinetic energy (KE). Thus, in this case, where gravity is the only force doing work, mechanical energy (PE + KE) is conserved (not lost). Example: When you throw a ball vertically upward, the work done by your hand gives it kinetic energy. As the ball rises, it loses KE and gains PE. When it comes to a stop at its highest point, it has only PE. As it start to fall, the PE is converted back into KE. If there were no air friction, when it reached the level where it left your hand, it would have the same KE again.