1. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Hewitt/Lyons/Suchocki/Yeh Conceptual Integrated Science Chapter 4 MOMENTUM AND ENERGY

2. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley This lecture will help you understand: Momentum Impulse Impulse–Momentum Relationship Conservation of Momentum Work Energy Power Potential Energy Kinetic Energy The Work-Energy Theorem Kinetic Energy and Momentum Conservation of Energy Machines Efficiency

3. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Momentum Momentum—is ________ in _______ __________________________________ __________________________________ __________________________________ momentum = ____ ____

4. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Momentum Momentum = ______  __________ or Momentum = mass  ______ (_________________________) Momentum = mv _______ ____ or high ______  high _________ high ______ and high velocity  higher __________ _______ mass or low ________  low ____________ low mass and low velocity  lower momentum

5. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley _______________

6. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley A moving object has A.momentum. B.energy. C.speed. D.all of the above. Momentum CHECK YOUR NEIGHBOR

7. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley When the speed of an object is doubled, its momentum A.remains unchanged in accord with the conservation of momentum. B.doubles. C.quadruples. D.decreases. Momentum CHECK YOUR NEIGHBOR

8. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Impulse Impulse- _______________________________ ____________ for impulse: Impulse = _______  _______ = ___ great force for ________ time  _________ impulse same force for __________ time  __________ impulse

9. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley When the force that produces an impulse acts for twice as much time, the impulse is A.not changed. B.doubled. C.increased by four times. D.decreased by half. Impulse CHECK YOUR NEIGHBOR

10. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley _______ - _________ Relationship The __________ in ____________ of an object is ________ to the _______ applied to it __________ by the ________ interval during which the ________ is ________.

11. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Impulse–Momentum Relationship Equation: ___________ = change in momentum or ______  ______ = ____ __________ _______ force, ______ change in velocity  ______ change in ________ _______ force for short time  ________ change in _________ _____ force for _______ time  ____ change in _________

12. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Impulse–Momentum Relationship Cases of momentum changes: _____________ Momentum ____________________________________________ _____________________________________________ Examples: __________ cannons have ___ barrels for ________ range A golfer _______ _________ while teeing off

13. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley A cannonball shot from a cannon with a long barrel will emerge with greater speed, because the cannonball receives a greater A.average force. B.impulse. C.both of the above. D.neither of the above. Impulse–Momentum Relationship CHECK YOUR NEIGHBOR

14. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Impulse–Momentum Relationship Cases of momentum changes: ______________ Momentum____________________________________________ Examples: _______ into a _________ versus a brick ______ _________ into a _______ net versus onto solid _____

15. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley A fast-moving car hitting a haystack or hitting a cement wall produces vastly different results. Both experience A.the same change in momentum. B.the same impulse. C.the same force. D.A and B. Impulse–Momentum Relationship CHECK YOUR NEIGHBOR

16. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley When a dish falls, will the change in momentum be less if it lands on a carpet than if it lands on a hard floor? (Careful!) A.No, both are the same. B.Yes, less if it lands on the carpet. C.No, less if it lands on a hard floor. D.No, more if it lands on a hard floor. Impulse–Momentum Relationship CHECK YOUR NEIGHBOR

17. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley _______________ of Momentum In _______ case, the _________ of a system _________ _______ unless it is ________ on by ___________ forces. A system will have the _______ momentum _______ ______ and ______ the interaction occurs. When the momentum does _____ change, we say it is ________________.

18. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Conservation of Momentum Law of ______________ of ___________:______________________________________ ____________ form: (_____ momentum) ___ =(____ momentum)___

19. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Conservation of Momentum Collisions When objects ______ in the __________ of external forces, _______________________________________________ Examples: _________ collisions

20. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Conservation of Momentum Elastic collision _____________________________________________ _____________________________________________ _____________________________________________

21. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Conservation of Momentum Moving Ball A __________ Ball B, ______ at ___. Ball A comes to ____, and Ball B moves ___ with a ________ _____ to the ____ velocity of Ball A. Momentum is ____________ from Ball A to Ball B.

22. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Conservation of Momentum ______________ collision ______________________________________ ______________________________________

23. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Freight Car A is moving toward identical Freight Car B that is at rest. When they collide, both freight cars couple together. Compared with the initial speed of Freight Car A, the speed of the coupled freight cars is A.the same. B.half. C.twice. D.none of the above. Conservation of Momentum CHECK YOUR NEIGHBOR

24. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Work is defined ______________________________________ _________________________________ (in the same direction as the force). ______________________________________ ______________________________________ ______________________________________

25. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Work Two things enter where work is done: _____________ of force ___________ of something ___ that ________ Work done on the object ___________________ by the ________________________ ________________________.

26. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley If you push against a stationary brick wall for several minutes, you do no work A.on the wall. B.at all. C.both of the above. D.none of the above. Work CHECK YOUR NEIGHBOR

27. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Work The quantity of work done ________________________________________ ____________________________ in the _______ in which the force acts. Work falls into two categories: work done ______________ another force work done to ________ ____ ______ of an object

28. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Work is done in lifting a barbell. How much work is done in lifting a twice-as-heavy barbell the same distance? A.Twice as much. B.Half as much. C.The same. D.Depends on the speed of the lift. Work CHECK YOUR NEIGHBOR

29. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley You do work when pushing a cart with a constant force. If you push the cart twice as far, then the work you do is A.less than twice as much. B.twice as much. C.more than twice as much. D.zero. Work CHECK YOUR NEIGHBOR

30. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Energy ______________________________________ The _______ of _______ are observed only when it is being _________ from ___ place to ______ or _____________ from ____ form to _________. Unit for energy: _________ Both _____ and _______ are measured in _____.

31. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Power ____________________________________ or the ______ at which ________ is _______ from ______ ________ to ______________. Equation for power: Units for power: _________________, or ____ (One watt = 1 joule of work per second)

32. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley A job can be done slowly or quickly. Both may require the same amount of work, but different amounts of A.energy. B.momentum. C.power. D.impulse. Power CHECK YOUR NEIGHBOR

33. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Potential Energy is defined ______________________________________ ____________. In its stored state, ________ has the ___________ for doing work. Examples: __________ bow ________________ rubber band ___________ ram of a pile driver

34. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Potential Energy The amount of gravitational potential energy possessed by an elevated object_________ _____________________________________ _____________________________________. _____ done ______ _____ required to move it _______  the _____ distance moved (______). The upward force when moved at constant velocity is the weight, _____, of the object. So the work done in lifting it through ______ h is the product mgh.

35. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley _____________ Energy Equation for gravitational potential energy: PE = ________________ or PE = ___________ _______________ potential energy examples: Water in an ___________ reservoir The elevated ram of a pile driver

36. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Does a car hoisted for repairs in a service station have increased potential energy relative to the floor? A.Yes. B.No. C.Sometimes. D.Not enough information. Potential Energy CHECK YOUR NEIGHBOR

37. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Kinetic Energy is defined as the energy of a moving body Equation for kinetic energy: Kinetic energy = 1 / 2 mass  speed 2 or Kinetic energy = 1 / 2 mv 2 small changes in speed  large changes in kinetic energy

38. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Must a car with momentum have kinetic energy? A.Yes, due to motion alone. B.Yes, when motion is nonaccelerated. C.Yes, because speed is a scalar and velocity is a vector quantity. D.No. Kinetic Energy CHECK YOUR NEIGHBOR

39. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley The Work-Energy Theorem When work is done on an object to change its kinetic energy, the amount of work done is equal to the change in kinetic energy. Equation for work-energy theorem: Net work = __________________ If there is ___ _________ in object’s energy, then __ work is done. Applies to ______________ energy: For a ________ held stationary, _____ further work is done  no further change in _______________ Applies to ______________ energy: The more __________ energy something has  the _________ work is ____________ to _________ it

40. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Consider a problem that asks for the distance a fast- moving crate slides across a factory floor in coming to a stop. The most useful equation for solving this problem is A. F = ma. B. Ft =  mv. C. KE = 1 / 2 mv 2. D.Fd =  1 / 2 mv 2. The Work-Energy Theorem CHECK YOUR NEIGHBOR

41. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley The work done in braking a moving car to a stop is the force of tire friction  stopping distance. If the initial speed of the car is doubled, the stopping distance is A.actually less. B.about the same. C.twice. D.none of the above. The Work-Energy Theorem CHECK YOUR NEIGHBOR

42. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley _________ Energy and Momentum Comparison of _______ _______ and _________ ______ depend on ______ and _________— _________ depends on ______ and ______. ___ depends on ______ and the ________ of its speed. _________ is a vector quantity. ________ energy is a ____________ quantity.

43. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley ____________ of Energy __________________ is defined in everyday language as “______”—in physics, to “______ ____________.” _______ of ____________ of _________: In the ___________ of ___________ work input or output, the energy of a system remains unchanged. _______ cannot be ________ or __________.

44. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Conservation of Energy A situation to ponder… Consider the _______ of a _______ and _________. In drawing the ______, we do work on the system and give it ________ energy. When the bowstring is ________, most of the ___________ energy is _____________ to the arrow as ________ energy and some as _______ to the bow.

45. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Suppose the potential energy of a drawn bow is 50 joules, and the kinetic energy of the shot arrow is 40 joules. Then A.energy is not conserved. B.10 joules go to warming the bow. C.10 joules go to warming the target. D.10 joules is mysteriously missing. A situation to ponder… CHECK YOUR NEIGHBOR

46. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley _____________ Machine — a device for __________ force or changing the __________ of force. No machine can put out more ________ than is put into it. _________ energy; it can only transfer or _____________ energy.

47. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Machines Equation: work ______ = work ______ (______  distance)___ =(____  distance)____ Example: a _______ lever small input force over a ____ distance  large _______ ______ over a _______ distance

48. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley In an ideal pulley system, a woman lifts a 100-N crate by pulling a rope downward with a force of 25 N. For every one-meter length of rope she pulls downward, the crate rises A.50 centimeters. B.45 centimeters. C.25 centimeters. D.none of the above. Machines CHECK YOUR NEIGHBOR

49. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley Efficiency Efficiency— ________________________________________ _______________________________________. Equation for efficiency: a machine with ___ efficiency  greater amount of _____ wasted as heat Some ______ is always _________ as heat, which means that no machine is ever 100% ________.

50. Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley A certain machine is 30% efficient. This means the machine will convert A.30% of the energy input to useful work—70% of the energy input will be wasted. B.70% of the energy input to useful work—30% of the energy input will be wasted. C.as strange as it may seem, both of the above. D.none of the above. Efficiency CHECK YOUR NEIGHBOR