Introduction to Mechanics Conservative and Nonconservative Forces Potential Energy
|
|
|
- Willis Stone
- 6 years ago
- Views:
Transcription
1 Introduction to Mechanics Conservative and Nonconservative Forces Potential Energy Lana Sheridan De Anza College Mar 20, 2018
2 Last time work of varying force kinetic energy work-kinetic energy theorem power
3 Overview on more power example conservative and nonconservative forces friction potential energy potential energy diagrams (?)
4 Power Power the rate of energy transfer to a system or the rate of work done on a system. The average power is defined as P = W t Unit: the Watt. 1 J/s = 1 W P = F v
5 Another Power Example /05 17:24 Page 197 A car drives up a hill at a constant speed, v. If the hill is inclined at an angle of 5.00, the mass of the car is 1500 kg, the force of friction is 100 N, the force of air resistance is 150 N, and v = 15 m/s, what power must be delivered by the engine? SKETCH: CHAPTER SUMMARY 197 y x N N N F friction F F F fric F F friction F air res mg F air res mg F air res mg sin mg cos 1 Figure from Walker, page 208. mg
6 Another Power Example A car drives up a hill at a constant speed, v. If the hill is inclined at an angle of 5.0, the mass of the car is 1500 kg, the force of friction is 100 N, the force of air resistance is 150 N, and v = 15 m/s, what power must be delivered by the engine? x-dir: Power: F net,x = m a 0 x F mg sin θ F fric F ar = 0 P = Fv F = 1281 N N N F = 1531 N P = (1531 N)(15 m/s) P = 23 kw
7 Work Contrast done by gravity this with W g the = Fd force cos(180 of kinetic ) = mgh. friction, which is noncon slide a box of mass m across the floor with constant speed, as shown i in the process gives the box an equivalent amount of kinetic energy. Work Done Lifting a Box Work done by person (applied Work done force) by person W = mgh app = Fd cos(0 ) = Work mgh. done by gr h
8 R 8 Conservative and Nonconservative Forces The work done by gravity when raising and lowering an object around a closed path is zero. POTENTIAL ENERGY AND CONSERVATION OF ENERGY Work done by gravity on is zero no work on the two horints of the path. On the two ents, the amounts of work l in magnitude but oppoherefore, the total work ity on this or any closed D W = 0 mg Side View C W = mgh W = mgh h mg W = 0 mg A B mg The path taken doesn t matter; if it comes back to the start, the work done is zero. but it does positive work from D to A (displacement and force are in the same direction). Hence, W BC = -mgh and W DA = mgh. As a result, the total work done by gravity is zero: Forces (like gravity) that behave W total = 0 this + 1-mgh2 way + are 0 + mgh called = 0 conservative forces. With friction, the results are quite different. If we push the box around the
9 Conservative and Nonconservative Forces Conservative Force: Definition 1 The work done by friction when pushing an object around a closed A conservative force is a force that does zero total work on any closed path. path is not zero. Work done by friction th is nonzero e by friction when an hrough a distance d is s, the total work done by osed path is nonzero. In qual to - 4 m k mgd. W total = 1-m k mgd2 + 1-m k mgd2 + 1-m k mgd2 + 1-m k mgd2 = -4 m k mgd These results lead to the following definition of a conservative force: D W = µ k mgd f k C Top View f k W = µ k mgd W = µ k mgd f k d f k A B W = µ k mgd d Forces (like friction) where the work done over a closed path is not zero are called nonconservative forces.
10 The differences between conservative and nonconservative forces are even more Nonconservative apparent if we consider moving Forces: an object Friction around a closed path. Consider, for example, the path shown in Figure 8 3. If we move a box of mass m along this path, The the total work work done by gravity kineticis friction the sum of isthe always work done negative. on each segment of the path; that is W total = W AB + W BC + W CD + W DA. The work done by gravity from A to B and from C to D is zero, since the force is at right angles to the displacement on these segments. Thus C, gravity does negative work (displacement and force are in opposite directions), Kinetic friction points in Wthe opposite direction to the velocity / AB = W CD = 0. On the segment from B to instantaneous displacement. Work = k mgd k N k N mg N d FIGURE 8 2 Pushing a box against frictio When the box comes to rest work. Friction W fric = f k d = µ k Nd where d is the distance the object moves along the surface.
11 Nonconservative Forces: Friction Air resistance is another nonconservative force. When a force does negative work on a system, energy is transferred out of the system. In the case of kinetic friction, this energy increases the temperature of the two surfaces that rub on each other, and may also leave as sound waves. This energy is lost to the system, but not to the universe.
12 Nonconservative Forces: Friction Example Calculate the work done by friction as a 3.2-kg box is slid along a entifies floor problems from of biological point A or to medical point interest. B along Red paths bullets 1, (,, ) 2, and 3. are Assume used that the coefficient of kinetic friction between the box and the floor is s is, 2, m 1.0 m 1.0 m 4.0 m 1.0 m 1.0 m B 2.0 m A 2.0 m m 1.0 m 3.0 m 3 Top View FIGURE 8 18 Problem 2 1 Walker, Ch 8, prob.
13 distance is h, the work you do on the box is W = mgh. If you now release the box and allow it to drop back to the floor, gravity does the same work, in the process gives the box an equivalent amount of kinetic energy. Conservative Forces: Work Done Lifting W = mgh, a Box and Work done by person (applied force) W = Fd cos(0 ) = mgh. Work done by person = mgh Work done by gravity = mgh FIGURE 8 Lifting a bo stant speed box is releas work on the conservativ h Contrast Whenthis box with falls, the force this energy of kinetic becomes friction, which kinetic is nonconservative. energy. To slide a box of mass m across the floor with constant speed, as shown in Figure 8 2, you must Wexert net = a mgh force of = magnitude K. m k N = m k mg. After sliding the box a distance d, the work you have done is W = m k mgd. In this case, when you release the box it simply stays put friction does no work on it after you let go. Thus, the work
14 in the process gives the box an equivalent amount of kinetic energy. Conservative Forces: Potential Energy Work done by person = mgh Work done by gravity = mgh FIGURE 8 Lifting a bo stant speed box is releas work on the conservativ h Contrast this with the force of kinetic friction, which is nonconservative. To slide a box of mass m across the floor with constant speed, as shown in Figure 8 2, you must exert a force of magnitude m k N = m k mg. After sliding the box a distance energy. d, the work you have done is W = m k mgd. In this case, when you release the box it simply stays put friction does no work on it after you let go. Thus, the work done by a nonconservative force cannot be recovered later as kinetic energy; instead, it is converted to other forms of energy, such as a slight warming of the When the box is in the air, it has the potential to have kinetic The man put in work lifting it, as long as the box is held in the air, this energy is stored.
15 Conservative Forces: Potential Energy Any box that has been lifted a height h has had the same work done on it: mgh. The path the box took to get to that height doesn t matter. This is because gravity is a conservative force.
16 Conservative Forces: Potential Energy Any box that has been lifted a height h has had the same work done on it: mgh. The path the box took to get to that height doesn t matter. This is because gravity is a conservative force. For any conservative force acting on an object, we can say that the object has some amount of stored energy that depends on its configuration.
17 Conservative Forces: Potential Energy Any box that has been lifted a height h has had the same work done on it: mgh. The path the box took to get to that height doesn t matter. This is because gravity is a conservative force. For any conservative force acting on an object, we can say that the object has some amount of stored energy that depends on its configuration. Potential energy energy that system has as a result of its configuration. Is always the result of the effect of a conservative force.
18 Potential Energy Potential energy energy that system has as a result of its configuration. Is always the result of the effect of a conservative force. Only conservative forces can have associated potential energies! If a nonconservative force acts, any work done to displace the system (at constant velocity) leaves the system again as heat and sound. That energy isn t stored no potential energy.
19 Gravitational Potential Energy The change of potential energy when lifting an object of mass m near the Earth s surface: U = mg( h) If we choose the convention that U = 0 at the Earth s surface, then an object (mass m) at a height h has gravitational potential energy: U = mgh
20 Gravitational Potential Energy The change of potential energy when lifting an object of mass m near the Earth s surface: U = mg( h) One technical point: in order for a box to be at one height or another, we need the Earth (which creates the gravitational force on the box) to be part of our system description.
21 Gravitational Potential Energy The change of potential energy when lifting an object of mass m near the Earth s surface: U = mg( h) One technical point: in order for a box to be at one height or another, we need the Earth (which creates the gravitational force on the box) to be part of our system description. The configuration of the system refers to how close the box is to center of the Earth. To have a potential energy, we must include the Earth in the system and make the weight of the box an internal force.
22 tional potential energy of the stone Earth system (a) before the stone is released and (b) when it reaches the bottom of the well? (c) What is the change in gravitational potential energy of the system from release to reaching the bottom of the well? Gravitational Potential Energy or on nt raec- e- w- ct rts so es. of nd arnd ur ge he 42. A 400-N child is in a swing that is attached to a pair W of ropes 2.00 m long. Find the gravitational potential energy of the child Earth system relative to the child s lowest position when (a) the ropes are horizontal, (b) the ropes make a angle with the vertical, and (c) the child is at the bottom of the circular arc. Section 7.7 Conservative and Nonconservative Forces 43. A 4.00-kg particle moves M from the origin to position, having coordi- Q/C nates x m and y m (Fig. P7.43). One force on the particle is the gravitational force y (m) er 1 Problem from Serway & Jewett, 9th ed, page 207. (5.00, 5.00)
23 tional potential energy of the stone Earth system (a) before the stone is released and (b) when it reaches the bottom of the well? (c) What is the change in gravitational potential energy of the system from release to reaching the bottom of the well? Gravitational Potential Energy or on nt raec- e- w- ct rts so es. of nd arnd ur ge he er 42. A 400-N child is in a swing that is attached to a pair W of ropes 2.00 m long. Find the gravitational potential energy of the child Earth system relative to the child s lowest position when (a) the ropes are horizontal, (b) the ropes make a angle with the vertical, and (c) the child is at the bottom of the circular arc. (a) Section U = (mg)y 7.7 Conservative = (400 N)(2and m) Nonconservative = 800J Forces 43. A 4.00-kg particle moves y (m) M from the origin to position, having coordi- Q/C (5.00, 5.00) nates x m and y m (Fig. P7.43). One force on the particle is 1 Problem the gravitational from Serway & Jewett, force 9th ed, page 207.
24 tional potential energy of the stone Earth system (a) before the stone is released and (b) when it reaches the bottom of the well? (c) What is the change in gravitational potential energy of the system from release to reaching the bottom of the well? Gravitational Potential Energy or on nt raec- e- w- ct rts so es. of nd arnd ur ge he er 42. A 400-N child is in a swing that is attached to a pair W of ropes 2.00 m long. Find the gravitational potential energy of the child Earth system relative to the child s lowest position when (a) the ropes are horizontal, (b) the ropes make a angle with the vertical, and (c) the child is at the bottom of the circular arc. (a) Section U = (mg)y 7.7 Conservative = (400 N)(2and m) Nonconservative = 800J Forces 43. A 4.00-kg particle moves y (m) (b) U = (mg)y = (400 N)(2 m)(1 cos 30 from the origin to position, having coordi- ) = 107J M Q/C (5.00, 5.00) nates x m and y m (Fig. P7.43). One force on the particle is 1 Problem the gravitational from Serway & Jewett, force 9th ed, page 207.
25 tional potential energy of the stone Earth system (a) before the stone is released and (b) when it reaches the bottom of the well? (c) What is the change in gravitational potential energy of the system from release to reaching the bottom of the well? Gravitational Potential Energy or on nt raec- e- w- ct rts so es. of nd arnd ur ge he er 42. A 400-N child is in a swing that is attached to a pair W of ropes 2.00 m long. Find the gravitational potential energy of the child Earth system relative to the child s lowest position when (a) the ropes are horizontal, (b) the ropes make a angle with the vertical, and (c) the child is at the bottom of the circular arc. (a) Section U = (mg)y 7.7 Conservative = (400 N)(2and m) Nonconservative = 800J Forces 43. A 4.00-kg particle moves y (m) (b) U = (mg)y = (400 N)(2 m)(1 cos 30 from the origin to position = 0., having coordi- ) = 107J M (c) Q/CU (5.00, 5.00) nates x m and y m (Fig. P7.43). One force on the particle is 1 Problem the gravitational from Serway & Jewett, force 9th ed, page 207.
26 Spring Force: Another Conservative Force The spring force is also a conservative force. If we stretch a spring, we can say that the spring stores the energy. That energy is converted to kinetic energy when the end of the spring is released.
27 Spring Force: Another Conservative Force The spring force is also a conservative force. If we stretch a spring, we can say that the spring stores the energy. That energy is converted to kinetic energy when the end of the spring is released. There is also spring potential energy! Choosing U = 0 when the spring is at its natural length (relaxed): U = 1 2 kx 2 (The spring must be part of our system.)
28 Spring Force Example Ch 8, # 14 Pushing on the pump of a soap dispenser compresses a small spring. When the spring is compressed 0.50 cm, its potential energy is J. (a) What is the force constant of the spring? (b) What compression is required for the spring potential energy to equal J?
29 Spring Force Example Ch 8, # 14 Pushing on the pump of a soap dispenser compresses a small spring. When the spring is compressed 0.50 cm, its potential energy is J. (a) What is the force constant of the spring? (b) What compression is required for the spring potential energy to equal J? U = 1 2 kx 2
30 Spring Force Example Ch 8, # 14 Pushing on the pump of a soap dispenser compresses a small spring. When the spring is compressed 0.50 cm, its potential energy is J. (a) What is the force constant of the spring? (b) What compression is required for the spring potential energy to equal J? U = 1 2 kx 2 (a) k = 2U x 2 = N/cm = N/m
31 Spring Force Example Ch 8, # 14 Pushing on the pump of a soap dispenser compresses a small spring. When the spring is compressed 0.50 cm, its potential energy is J. (a) What is the force constant of the spring? (b) What compression is required for the spring potential energy to equal J? U = 1 2 kx 2 (a) k = 2U x 2 (b) x = 2U k = N/cm = N/m = 0.92 cm
32 Summary power example conservative and nonconservative forces potential energy Homework Walker Physics: Ch 8, onward from page 243. Questions: 1, 3; Problems: 2, 3, 9, 13, 15, 17
Introduction to Mechanics Potential Energy Energy Conservation
Introduction to Mechanics Potential Energy Energy Conservation Lana Sheridan De Anza College Nov 28, 2017 Last time power conservative and nonconservative forces friction Overview conservative forces and
Energy Potential Energy Conservative and Nonconservative Forces
Energy Potential Energy Conservative and Nonconservative Forces Lana Sheridan De Anza College Oct 26, 2017 Last time Work as an integral Kinetic Work-Kinetic theorem Potential Overview Gravitational and
Energy Potential Energy and Force Conservation Laws Isolated and Nonisolated Systems
Energy Potential Energy and Force Conservation Laws Isolated and Nonisolated ystems Lana heridan De Anza College Oct 27, 2017 Last time gravitational and spring potential energies conservative and nonconservative
PHYS Summer Professor Caillault Homework Solutions. Chapter 8
PHYS 1111 - Summer 007 - Professor Caillault Homework Solutions Chapter 8 5. Picture the Problem The physical situation is depicted at right. for the Strategy Use W sp = 1 k x i x f work done by the spring.
Introduction to Mechanics Non-uniform Circular Motion Introducing Energy
Introduction to Mechanics Non-uniform Circular Motion Introducing Energy Lana Sheridan De Anza College Nov 20, 2017 Last time applying the idea of centripetal force banked turns Overview non-uniform circular
Introduction to Mechanics Friction Examples Friction Springs
Introduction to Mechanics Friction Examples Friction Springs Lana Sheridan De Anza College Mar 7, 2018 Last time kinetic and static friction friction examples Overview one more friction example springs
Chapter 6 Work and Energy
Chapter 6 Work and Energy Midterm exams will be available next Thursday. Assignment 6 Textbook (Giancoli, 6 th edition), Chapter 6: Due on Thursday, November 5 1. On page 162 of Giancoli, problem 4. 2.
(35+70) 35 g (m 1+m 2)a=m1g a = 35 a= =3.27 g 105
Coordinator: Dr. W. L-Basheer Monday, March 16, 2015 Page: 1 Q1. 70 N block and a 35 N block are connected by a massless inextendable string which is wrapped over a frictionless pulley as shown in Figure
ENERGY. Conservative Forces Non-Conservative Forces Conservation of Mechanical Energy Power
ENERGY Conservative Forces Non-Conservative Forces Conservation of Mechanical Energy Power Conservative Forces A force is conservative if the work it does on an object moving between two points is independent
Chapter 6 Energy and Oscillations
Chapter 6 Energy and Oscillations Conservation of Energy In this chapter we will discuss one of the most important and fundamental principles in the universe. Energy is conserved. This means that in any
Homework #5. Ph 231 Introductory Physics, Sp-03 Page 1 of 4
Homework #. Ph Introductory Physics, Sp-0 Page of -A. A 7 kg block moves in a straight line under the influence of a force that varies with position as shown in the figure at the right. If the force is
Essentially, the amount of work accomplished can be determined two ways:
1 Work and Energy Work is done on an object that can exert a resisting force and is only accomplished if that object will move. In particular, we can describe work done by a specific object (where a force
Mechanics and Heat. Chapter 5: Work and Energy. Dr. Rashid Hamdan
Mechanics and Heat Chapter 5: Work and Energy Dr. Rashid Hamdan 5.1 Work Done by a Constant Force Work Done by a Constant Force A force is said to do work if, when acting on a body, there is a displacement
Old Exams Questions Ch. 8 T072 Q2.: Q5. Q7.
Old Exams Questions Ch. 8 T072 Q2.: A ball slides without friction around a loop-the-loop (see Fig 2). A ball is released, from rest, at a height h from the left side of the loop of radius R. What is the
Other Examples of Energy Transfer
Chapter 7 Work and Energy Overview energy. Study work as defined in physics. Relate work to kinetic energy. Consider work done by a variable force. Study potential energy. Understand energy conservation.
PHYS 101 Previous Exam Problems. Kinetic Energy and
PHYS 101 Previous Exam Problems CHAPTER 7 Kinetic Energy and Work Kinetic energy Work Work-energy theorem Gravitational work Work of spring forces Power 1. A single force acts on a 5.0-kg object in such
Chapter 10-Work, Energy & Power
DULLES HIGH SCHOOL Chapter 10-Work, Energy & Power Energy Transformations Judy Matney 1/12/2016 In this chapter, we will study the concepts of force and work; we will understand the transformations of
Potential Energy. Serway 7.6, 7.7;
Potential Energy Conservative and non-conservative forces Gravitational and elastic potential energy Mechanical Energy Serway 7.6, 7.7; 8.1 8.2 Practice problems: Serway chapter 7, problems 41, 43 chapter
Work and energy. 15 m. c. Find the work done by the normal force exerted by the incline on the crate.
Work and energy 1. A 10.0-kg crate is pulled 15.0 m up along a frictionless incline as shown in the figure below. The crate starts at rest and has a final speed of 6.00 m/s. motor 15 m 5 a. Draw the free-body
DEVIL PHYSICS THE BADDEST CLASS ON CAMPUS IB PHYSICS
DEVIL PHYSICS THE BADDEST CLASS ON CAMPUS IB PHYSICS LSN -3: WORK, ENERGY AND POWER Questions From Reading Activity? Essential Idea: The fundamental concept of energy lays the basis upon which much of
Phys101 Lectures 9 and 10 Conservation of Mechanical Energy
Phys101 Lectures 9 and 10 Conservation of Mechanical Energy Key points: Conservative and Nonconservative Forces Potential Energy Generalized work-energy principle Mechanical Energy and Its Conservation
Physics 111. Lecture 15 (Walker: 7.1-2) Work & Energy March 2, Wednesday - Midterm 1
Physics 111 Lecture 15 (Walker: 7.1-2) Work & Energy March 2, 2009 Wednesday - Midterm 1 Lecture 15 1/25 Work Done by a Constant Force The definition of work, when the force is parallel to the displacement:
Physics 2414 Group Exercise 8. Conservation of Energy
Physics 244 Group Exercise 8 Name : OUID : Name 2: OUID 2: Name 3: OUID 3: Name 4: OUID 4: Section Number: Solutions Solutions Conservation of Energy A mass m moves from point i to point f under the action
Conceptual Physics Energy
Conceptual Physics Energy Lana Sheridan De Anza College July 12, 2017 Last time Newton s third law momentum impulse momentum conservation Overview energy work kinetic energy potential energy energy conservation
Work Done by a Constant Force
Work and Energy Work Done by a Constant Force In physics, work is described by what is accomplished when a force acts on an object, and the object moves through a distance. The work done by a constant
= 1 2 kx2 dw =! F! d! r = Fdr cosθ. T.E. initial. = T.E. Final. = P.E. final. + K.E. initial. + P.E. initial. K.E. initial =
Practice Template K.E. = 1 2 mv2 P.E. height = mgh P.E. spring = 1 2 kx2 dw =! F! d! r = Fdr cosθ Energy Conservation T.E. initial = T.E. Final (1) Isolated system P.E. initial (2) Energy added E added
Energy Work Kinetic Energy Potential Energy
Energy Work Kinetic Energy Potential Energy Lana Sheridan De Anza College Oct 25, 2017 Last time energy work Overview Work as an integral Kinetic energy Work-Kinetic energy theorem Potential energy N through
MECHANICAL (TOTAL) ENERGY
DO NOW: 1/19 If you haven t already, please take the short google form survey posted on Edmodo Please turn in your Work done by friction Lab in the top tray POTENTIAL ENERGY Stored energy An object that
PSI AP Physics I Work and Energy
PSI AP Physics I Work and Energy Multiple-Choice questions 1. A driver in a 2000 kg Porsche wishes to pass a slow moving school bus on a 4 lane road. What is the average power in watts required to accelerate
Chapter 5. Work and Energy. continued
Chapter 5 Work and Energy continued 5.2 Work on a Spring & Work by a Spring HOOKE S LAW Force Required to Distort an Ideal Spring The force applied to an ideal spring is proportional to the displacement
Mechanics. Time (s) Distance (m) Velocity (m/s) Acceleration (m/s 2 ) = + displacement/time.
Mechanics Symbols: Equations: Kinematics The Study of Motion s = distance or displacement v = final speed or velocity u = initial speed or velocity a = average acceleration s u+ v v v u v= also v= a =
Physics 100A Summer 2016 Chapter 8
Physics 00A Summer 06 Chapter 8 Solutions are provided only for problems from your textbook. The other problems already have so much guidance and notes that you should be able to understand where you have
General Physics I Work & Energy
General Physics I Work & Energy Forms of Energy Kinetic: Energy of motion. A car on the highway has kinetic energy. We have to remove this energy to stop it. The brakes of a car get HOT! This is an example
Momentum & Energy Review Checklist
Momentum & Energy Review Checklist Impulse and Momentum 3.1.1 Use equations to calculate impulse; momentum; initial speed; final speed; force; or time. An object with a mass of 5 kilograms is moving at
Chapter 8 Solutions. The change in potential energy as it moves from A to B is. The change in potential energy in going from A to B is
Chapter 8 Solutions *8. (a) With our choice for the zero level for potential energy at point B, U B = 0. At point A, the potential energy is given by U A = mgy where y is the vertical height above zero
PSI AP Physics C Work and Energy. (With Calculus) Multiple Choice Questions
PSI AP Physics C Work and Energy (With Calculus) Multiple Choice Questions 1. An object moves according to the function x = t 7/2 where x is the distance traveled and t is the time. Its kinetic energy
Conservative vs. Non-conservative forces Gravitational Potential Energy. Conservation of Mechanical energy
Next topic Conservative vs. Non-conservative forces Gravitational Potential Energy Mechanical Energy Conservation of Mechanical energy Work done by non-conservative forces and changes in mechanical energy
(A) 10 m (B) 20 m (C) 25 m (D) 30 m (E) 40 m
Work/nergy 1. student throws a ball upward where the initial potential energy is 0. t a height of 15 meters the ball has a potential energy of 60 joules and is moving upward with a kinetic energy of 40
AP Physics C: Work, Energy, and Power Practice
AP Physics C: Work, Energy, and Power Practice 1981M2. A swing seat of mass M is connected to a fixed point P by a massless cord of length L. A child also of mass M sits on the seat and begins to swing
Chapter 5. Work and Energy. continued
Chapter 5 Work and Energy continued 5.2 Work on a Spring & Work by a Spring Work done by applied force stretching (or compressing) a spring. Force is changing while stretching so use the average force.
Old Exam. Question Chapter 7 072
Old Exam. Question Chapter 7 072 Q1.Fig 1 shows a simple pendulum, consisting of a ball of mass M = 0.50 kg, attached to one end of a massless string of length L = 1.5 m. The other end is fixed. If the
Potential Energy & Conservation of Energy
PHYS 101 Previous Exam Problems CHAPTER 8 Potential Energy & Conservation of Energy Potential energy Conservation of energy conservative forces Conservation of energy friction Conservation of energy external
Energy Energy and Friction
Energy Energy and Friction Lana heridan De Anza College Oct 31, 2017 Last time energy conservation isolated and nonisolated systems Overview Isolated system example Kinetic friction and energy Practice
Lecture 10 Mechanical Energy Conservation; Power
Potential energy Basic energy Lecture 10 Mechanical Energy Conservation; Power ACT: Zero net work The system of pulleys shown below is used to lift a bag of mass M at constant speed a distance h from the
Slide. King Saud University College of Science Physics & Astronomy Dept. PHYS 103 (GENERAL PHYSICS) CHAPTER 8: POTENTIAL ENERGY LECTURE NO.
Slide King Saud University College of Science Physics & Astronomy Dept. PHYS 103 (GENERAL PHYSICS) CHAPTER 8: POTENTIAL ENERGY LECTURE NO. 11 THIS PRESENTATION HAS EEN PREPARED Y: DR. NASSR S. ALZAYED
Phys101 Lectures 9 and 10 Conservation of Mechanical Energy
Phys101 Lectures 9 and 10 Conservation of Mechanical Energy Key points: Conservative and Nonconservative Forces Potential Energy Generalized work-energy principle Mechanical Energy and Its Conservation
In-Class Problems 20-21: Work and Kinetic Energy Solutions
MASSACHUSETTS INSTITUTE OF TECHNOLOGY Department of Physics Physics 8.01T Fall Term 2004 In-Class Problems 20-21: Work and Kinetic Energy Solutions In-Class-Problem 20 Calculating Work Integrals a) Work
POTENTIAL ENERGY AND ENERGY CONSERVATION
7 POTENTIAL ENERGY AND ENERGY CONSERVATION 7.. IDENTIFY: U grav = mgy so ΔU grav = mg( y y ) SET UP: + y is upward. EXECUTE: (a) ΔU = (75 kg)(9.8 m/s )(4 m 5 m) = +6.6 5 J (b) ΔU = (75 kg)(9.8 m/s )(35
Review. Kinetic Energy Work Hooke s s Law Potential Energy Conservation of Energy Power 1/91
Review Kinetic Energy Work Hooke s s Law Potential Energy Conservation of Energy Power 1/91 The unit of work is the A. Newton B. Watt C. Joule D. Meter E. Second 2/91 The unit of work is the A. Newton
Conservation of Energy and Momentum
Conservation of Energy and Momentum Three criteria for Work There must be a force. There must be a displacement, d. The force must have a component parallel to the displacement. Work, W = F x d, W = Fd
Energy Energy and Friction
Energy Energy and Friction Lana Sheridan De Anza College Oct 31, 2017 Last time energy conservation isolated and nonisolated systems Overview Isolated system example Kinetic friction and energy Practice
PHYSICS - CLUTCH CH 07: WORK & ENERGY.
!! www.clutchprep.com INTRO TO ENERGY & ENERGY FORMS ENERGY: A physical quantity without a precise definition. We don't know exactly WHAT it is, but we know HOW it works. - Energy "exists" in many forms;
Physics 201, Midterm Exam 2, Fall Answer Key
Physics 201, Midterm Exam 2, Fall 2006 Answer Key 1) A constant force is applied to a body that is already moving. The force is directed at an angle of 60 degrees to the direction of the body s velocity.
1- A force F = ( 6ˆ i 2ˆ j )N acts on a particle that undergoes a displacement
1- A force F = ( 6ˆ i 2ˆ j )N acts on a particle that undergoes a displacement r = ( 3ˆ i + ˆ j )m. Find (a) the work done by the force on the particle and (b) the angle between F and r. 2- The force acting
(A) 10 m (B) 20 m (C) 25 m (D) 30 m (E) 40 m
PSI AP Physics C Work and Energy (Algebra Based) Multiple Choice Questions (use g = 10 m/s 2 ) 1. A student throws a ball upwards from the ground level where gravitational potential energy is zero. At
Name Lesson 7. Homework Work and Energy Problem Solving Outcomes
Physics 1 Name Lesson 7. Homework Work and Energy Problem Solving Outcomes Date 1. Define work. 2. Define energy. 3. Determine the work done by a constant force. Period 4. Determine the work done by a
Recall: Gravitational Potential Energy
Welcome back to Physics 15 Today s agenda: Work Power Physics 15 Spring 017 Lecture 10-1 1 Recall: Gravitational Potential Energy For an object of mass m near the surface of the earth: U g = mgh h is height
0J2 - Mechanics Lecture Notes 2
0J2 - Mechanics Lecture Notes 2 Work, Power, Energy Work If a force is applied to a body, which then moves, we say the force does work. In 1D, if the force is constant with magnitude F, and the body moves
Energy Power. Lana Sheridan. Nov 1, De Anza College
Energy Power Lana heridan De Anza College Nov 1, 2017 Overview Power Practice problems! Power Power the rate of energy transfer to a system. Power Power the rate of energy transfer to a system. The instantaneous
Chapter 6 Work, Energy, and Power. Copyright 2010 Pearson Education, Inc.
Chapter 6 Work, Energy, and Power What Is Physics All About? Matter Energy Force Work Done by a Constant Force The definition of work, when the force is parallel to the displacement: W = Fs SI unit: newton-meter
( ) = ( ) W net = ΔKE = KE f KE i W F. F d x. KE = 1 2 mv2. Note: Work is the dot product of F and d. Work-Kinetic Energy Theorem
Work-Kinetic Energy Theorem KE = 1 2 mv2 W F change in the kinetic energy of an object F d x net work done on the particle ( ) = ( ) W net = ΔKE = KE f KE i Note: Work is the dot product of F and d W g
Lecture 9. > Potential Energy. > Conservation of Energy. > Power. (Source: Serway; Giancoli) Villacorta--DLSUM-BIOPHY1-L Term01
Lecture 9 > Potential Energy > Conservation of Energy > Power (Source: Serway; Giancoli) 1 Conservative & Nonconservative Forces > The various ways work and energy appear in some processes lead to two
Created by T. Madas WORK & ENERGY. Created by T. Madas
WORK & ENERGY Question (**) A B 0m 30 The figure above shows a particle sliding down a rough plane inclined at an angle of 30 to the horizontal. The box is released from rest at the point A and passes
2 possibilities. 2.) Work is done and... 1.) Work is done and... *** The function of work is to change energy ***
Work-Energy Theorem and Energy Conservation *** The function of work is to change energy *** 2 possibilities 1.) Work is done and... or 2.) Work is done and... 1 EX: A 100 N box is 10 m above the ground
Work changes Energy. Do Work Son!
1 Work changes Energy Do Work Son! 2 Do Work Son! 3 Work Energy Relationship 2 types of energy kinetic : energy of an object in motion potential: stored energy due to position or stored in a spring Work
Lecture 3. > Potential Energy. > Conservation of Energy. > Power. (Source: Serway; Giancoli) Villacorta--DLSUM-SCIENVP-L Term01
Lecture 3 > Potential Energy > Conservation of Energy > Power (Source: Serway; Giancoli) 1 Conservative & Nonconservative Forces > Conservative forces allow objects to lose energy through work and gain
PHY 101. Work and Kinetic Energy 7.1 Work Done by a Constant Force
PHY 101 DR M. A. ELERUJA KINETIC ENERGY AND WORK POTENTIAL ENERGY AND CONSERVATION OF ENERGY CENTRE OF MASS AND LINEAR MOMENTUM Work is done by a force acting on an object when the point of application
Today: Work, Kinetic Energy, Potential Energy. No Recitation Quiz this week
Today: Work, Kinetic Energy, Potential Energy HW #4 due Thursday, 11:59 p.m. pm No Recitation Quiz this week 1 What is Energy? Mechanical Electromagnetic PHY 11 PHY 13 Chemical CHE 105 Nuclear PHY 555
l1, l2, l3, ln l1 + l2 + l3 + ln
Work done by a constant force: Consider an object undergoes a displacement S along a straight line while acted on a force F that makes an angle θ with S as shown The work done W by the agent is the product
Work Energy Review. 1. Base your answer to the following question on the information and diagram below and on your knowledge of physics.
Name: ate: 1. ase your answer to the following question on the information and diagram below and on your knowledge of physics. student pushes a box, weighing 50. newtons, 6.0 meters up an incline at a
Momentum & Energy Review Checklist
Momentum & Energy Review Checklist Impulse and Momentum 3.1.1 Use equations to calculate impulse; momentum; initial speed; final speed; force; or time. An object with a mass of 5 kilograms is moving at
Oscillations Simple Harmonic Motion
Oscillations Simple Harmonic Motion Lana Sheridan De Anza College Dec 1, 2017 Overview oscillations simple harmonic motion (SHM) spring systems energy in SHM pendula damped oscillations Oscillations and
Practice Exam 2. Name: Date: ID: A. Multiple Choice Identify the choice that best completes the statement or answers the question.
Name: Date: _ Practice Exam 2 Multiple Choice Identify the choice that best completes the statement or answers the question. 1. A roller-coaster car has a mass of 500 kg when fully loaded with passengers.
Dynamics Energy and Work
Dynamics Energy and Work Lana Sheridan De Anza College Oct 24, 2017 Last Time resistive forces: Drag Equation Drag Equation, One more point What if the object is not dropped from rest? (See Ch 6, prob
Introduction to Mechanics Applying Newton s Laws Friction
Introduction to Mechanics Applying Newton s Laws Friction Lana heridan De Anza College Mar 6, 2018 Last time kinds of forces and problem solving objects accelerated together the Atwood machine and variants
Practice Exam 2. Multiple Choice Identify the choice that best completes the statement or answers the question.
Practice Exam 2 Multiple Choice Identify the choice that best completes the statement or answers the question. 1. A roller-coaster car has a mass of 500.0 kg when fully loaded with passengers. At the bottom
Potential Energy and Conservation of Energy Chap. 7 & 8
Level : AP Physics Potential Energy and Conservation of Energy Chap. 7 & 8 Potential Energy of a System see p.191 in the textbook - Potential energy is the energy associated with the arrangement of a system
Static Equilibrium Gravitation
Static Equilibrium Gravitation Lana Sheridan De Anza College Dec 6, 2017 Overview One more static equilibrium example Newton s Law of Universal Gravitation gravitational potential energy little g Example
AP Physics C - Mechanics. Energy and Work. Slide 1 / 125 Slide 2 / 125. Slide 4 / 125. Slide 3 / 125. Slide 6 / 125. Slide 5 / 125.
Slide 1 / 125 Slide 2 / 125 AP Physics C - Mechanics Work and nergy 2015-12-03 www.njctl.org Slide 3 / 125 Slide 4 / 125 Table of Contents Click on the topic to go to that section nergy and Work Conservative
5.3. Conservation of Energy
5.3. Conservation of Energy Conservation of Energy Energy is never created or destroyed. Any time work is done, it is only transformed from one form to another: Kinetic Energy Potential Energy Gravitational,
b) What does each letter (or symbol) stand for in this equation? c) What are the corresponding SI units? (Write: symbol $ unit).
First Name: Last Name: 1. a) What is Newton s Second Law in formula form? b) What does each letter (or symbol) stand for in this equation? c) What are the corresponding SI units? (Write: symbol $ unit).
CPS lesson Work and Energy ANSWER KEY
CPS lesson Work and Energy ANSWER KEY 1. A ball feeder slowly pushes a bowling ball up a 1-m ramp to a height of 0.5 m above the floor. Neglecting friction, what constant force must be exerted on the 5-kg
Page 1. Name: 1) If a man walks 17 meters east then 17 meters south, the magnitude of the man's displacement is A) 34 m B) 30.
Name: 1) If a man walks 17 meters east then 17 meters south, the magnitude of the man's displacement is 34 m 30. m 17 m 24 m 2) The graph below represents the motion of a body that is moving with 6) Which
AP Physics C Mechanics
1 AP Physics C Mechanics Work and Energy 2015 12 03 www.njctl.org 2 Table of Contents Click on the topic to go to that section Energy and Work Conservative and Non Conservative Forces Conservation of Total
Power: Sources of Energy
Chapter 5 Energy Power: Sources of Energy Tidal Power SF Bay Tidal Power Project Main Ideas (Encyclopedia of Physics) Energy is an abstract quantity that an object is said to possess. It is not something
Chapters 10 & 11: Energy
Chapters 10 & 11: Energy Power: Sources of Energy Tidal Power SF Bay Tidal Power Project Main Ideas (Encyclopedia of Physics) Energy is an abstract quantity that an object is said to possess. It is not
Lecture 12 Friction &Circular. Dynamics
Lecture 12 Friction &Circular Exam Remarks Units, units, units Dynamics Drawing graphs with arrows and labels FBDs: ma is not a force! r(r) given, derive v(t), a(t) Circular motion: the velocity vector
W = F x W = Fx cosθ W = Fx. Work
Ch 7 Energy & Work Work Work is a quantity that is useful in describing how objects interact with other objects. Work done by an agent exerting a constant force on an object is the product of the component
AP PHYSICS 1 UNIT 4 / FINAL 1 PRACTICE TEST
AP PHYSICS 1 UNIT 4 / FINAL 1 PRACTICE TEST NAME FREE RESPONSE PROBLEMS Put all answers on this test. Show your work for partial credit. Circle or box your answers. Include the correct units and the correct
Chapters 10 & 11: Energy
Chapters 10 & 11: Energy Power: Sources of Energy Tidal Power SF Bay Tidal Power Project Main Ideas (Encyclopedia of Physics) Energy is an abstract quantity that an object is said to possess. It is not
0.1 Work. W net = T = T f T i,
.1 Work Contrary to everyday usage, the term work has a very specific meaning in physics. In physics, work is related to the transfer of energy by forces. There are essentially two complementary ways to
*Be able to use any previous concepts with work & energy, including kinematics & circular motion.
AP Physics 1 Chapter 6 Study Guide Work & Energy Topics: Work o W = Fdcosq, where q is the angle between F & d (only using part of force that makes the object move) o Force must make object move to do
The negative root tells how high the mass will rebound if it is instantly glued to the spring. We want
8.38 (a) The mass moves down distance.0 m + x. Choose y = 0 at its lower point. K i + U gi + U si + E = K f + U gf + U sf 0 + mgy i + 0 + 0 = 0 + 0 + kx (.50 kg)9.80 m/s (.0 m + x) = (30 N/m) x 0 = (60
The content contained in all sections of chapter 6 of the textbook is included on the AP Physics B exam.
WORK AND ENERGY PREVIEW Work is the scalar product of the force acting on an object and the displacement through which it acts. When work is done on or by a system, the energy of that system is always
Physics 111. Lecture 18 (Walker: 8.3-4) Energy Conservation I March 11, Conservation of Mechanical Energy
Physics 111 Lecture 18 (Walker: 8.3-4) Energy Conservation I March 11, 2009 Lecture 18 1/24 Conservation o Mechanical Energy Deinition o mechanical energy: (8-6) I the only work done in going rom the initial
Introduction to Mechanics Energy Conservation
Introduction to Mechanics Energy Conservation Lana Sheridan De Anza College Mar 22, 2018 Last time conservative forces and potential energy energy diagrams mechanical energy energy conservation Overview
A. B. C. D. E. v x. ΣF x
Q4.3 The graph to the right shows the velocity of an object as a function of time. Which of the graphs below best shows the net force versus time for this object? 0 v x t ΣF x ΣF x ΣF x ΣF x ΣF x 0 t 0
AP Physics C - Mechanics
Slide 1 / 125 Slide 2 / 125 AP Physics C - Mechanics Work and Energy 2015-12-03 www.njctl.org Table of Contents Slide 3 / 125 Click on the topic to go to that section Energy and Work Conservative and Non-Conservative
Physics 1A, Summer 2011, Summer Session 1 Quiz 3, Version A 1
Physics 1A, Summer 2011, Summer Session 1 Quiz 3, Version A 1 Closed book and closed notes. No work needs to be shown. 1. Three rocks are thrown with identical speeds from the top of the same building.
Machines: Can You lift a car?
Work=Force x Distance 10 m Units of work Nt-m=joules How much work? Machines: Can You lift a car? The ratio of the input force to the output force is called the Mechanical Advantage MA=5000/50=100 1 =