1. © Houghton Mifflin Harcourt Publishing Company Chapter 5 Definition of Work Work is done on an object when a force causes a displacement of the object. Work is done only when components of a force are parallel to a displacement. Section 1 Work

2. © Houghton Mifflin Harcourt Publishing Company Chapter 5 Definition of Work Section 1 Work

3. © Houghton Mifflin Harcourt Publishing Company Click below to watch the Visual Concept. Visual Concept Chapter 5 Section 1 Work Sign Conventions for Work

4. © Houghton Mifflin Harcourt Publishing Company Section 2 Energy Chapter 5 Kinetic Energy The energy of an object that is due to the object’s motion is called kinetic energy. Kinetic energy depends on speed and mass.

5. © Houghton Mifflin Harcourt Publishing Company Click below to watch the Visual Concept. Visual Concept Chapter 5 Section 2 Energy Kinetic Energy

6. © Houghton Mifflin Harcourt Publishing Company Section 2 Energy Chapter 5 Kinetic Energy, continued Work-Kinetic Energy Theorem –The net work done by all the forces acting on an object is equal to the change in the object’s kinetic energy. The net work done on a body equals its change in kinetic energy. W net = ∆KE net work = change in kinetic energy

7. © Houghton Mifflin Harcourt Publishing Company Click below to watch the Visual Concept. Visual Concept Chapter 5 Section 2 Energy Work-Kinetic Energy Theorem

8. © Houghton Mifflin Harcourt Publishing Company Section 2 Energy Chapter 5 Potential Energy Potential Energy is the energy associated with an object because of the position, shape, or condition of the object. Gravitational potential energy is the potential energy stored in the gravitational fields of interacting bodies. Gravitational potential energy depends on height from a zero level. PE g = mgh gravitational PE = mass  free-fall acceleration  height

9. © Houghton Mifflin Harcourt Publishing Company Click below to watch the Visual Concept. Visual Concept Chapter 5 Section 2 Energy Potential Energy

10. © Houghton Mifflin Harcourt Publishing Company Section 2 Energy Chapter 5 Potential Energy, continued Elastic potential energy is the energy available for use when a deformed elastic object returns to its original configuration. The symbol k is called the spring constant, a parameter that measures the spring’s resistance to being compressed or stretched.

11. © Houghton Mifflin Harcourt Publishing Company Chapter 5 Elastic Potential Energy Section 2 Energy

12. © Houghton Mifflin Harcourt Publishing Company Click below to watch the Visual Concept. Visual Concept Chapter 5 Section 2 Energy Spring Constant

13. © Houghton Mifflin Harcourt Publishing Company Section 3 Conservation of Energy Chapter 5 Conserved Quantities When we say that something is conserved, we mean that it remains constant.

14. © Houghton Mifflin Harcourt Publishing Company Section 3 Conservation of Energy Chapter 5 Mechanical Energy Mechanical energy is the sum of kinetic energy and all forms of potential energy associated with an object or group of objects. ME = KE + ∑PE Mechanical energy is often conserved. ME i = ME f initial mechanical energy = final mechanical energy (in the absence of friction)

15. © Houghton Mifflin Harcourt Publishing Company Click below to watch the Visual Concept. Visual Concept Chapter 5 Section 3 Conservation of Energy Conservation of Mechanical Energy

16. © Houghton Mifflin Harcourt Publishing Company Section 3 Conservation of Energy Chapter 5 Mechanical Energy, continued Mechanical Energy is not conserved in the presence of friction. As a sanding block slides on a piece of wood, energy (in the form of heat) is dissipated into the block and surface.

17. © Houghton Mifflin Harcourt Publishing Company Section 4 Power Chapter 5 Rate of Energy Transfer Power is a quantity that measures the rate at which work is done or energy is transformed. P = W/∆t power = work ÷ time interval An alternate equation for power in terms of force and speed is P = Fv power = force  speed

18. © Houghton Mifflin Harcourt Publishing Company Click below to watch the Visual Concept. Visual Concept Chapter 5 Section 4 Power Power