TB_chapter5

# TB_chapter5 - Chapter 5 Energy CHAPTER 5 Conceptual...

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Chapter 5, Energy C HAPTER 5 Conceptual Problems C1. Is it possible for the total mechanical energy of a moving particle to be negative? a. No, because a moving particle has positive kinetic energy. b. No, because potential energy cannot have a value more negative than the value of the positive kinetic energy of the particle. c. Only if friction is involved. d. yes C2. Three different mass projectiles are launched from the top of a building each at different angles of elevation. Each particle has the same initial kinetic energy. Which particle has the greatest kinetic energy just as it impacts with the ground? a. The one launched at the highest angle of elevation. b. The one with the highest mass. c. The one with the lowest mass. d. They all will have the same kinetic energy on impact. C3. Three different mass projectiles are launched from the top of a building each at different angles of elevation. Each particle has the same initial kinetic energy. Which particle has the greatest speed just as it impacts with the ground? a. The one launched at the highest angle of elevation. b. The one with the highest mass. c. The one with the lowest mass. d. They all will have the same speed on impact. C4. A block is projected with speed v across a horizontal surface and slides to a stop due to friction. The same block is then projected with the same speed v up an incline where is slides to a stop due to friction. In which case did the total mechanical energy of the block decrease the least? a. This problem cannot be solved since it was not indicated whether the horizontal surface and the incline both had the same coefficient of kinetic friction. b. The case on the horizontal surface had the least decrease in total mechanical energy. c. The case on the inclined surface had the least decrease in total mechanical energy. d. In both cases the decrease in mechanical energy was the same. C5. In a problem using energy considerations to solve for the speed of a ball thrown from the top of a building when it strikes the ground below, where should the potential energy have its zero value? a. It should be at the level from where the ball is thrown. b. It should be at the ground level where the ball hits. c. It should be slightly below ground level so the potential energy is always positive. d. It doesn’t matter since only differences in potential energy matter in solutions. 60

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Chapter 5, Energy 5.1 Work 1. The unit of work, joule, is dimensionally the same as: a. newton/second. b. newton/kilogram. c. newton-second. d. newton-meter. 2. Rupel pushes a box 5.00 m by applying a 25.0-N horizontal force. What work does she do? a. 10.0 J b. 25.0 J c. 125 J d. 550 J 3. A worker pushes a sled with a force of 40 N over a level distance of 6.0 m. If a frictional force of 24 N acts on the wheelbarrow in a direction opposite to that of the worker, what net work is done on the wheelbarrow? a. 240 J
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TB_chapter5 - Chapter 5 Energy CHAPTER 5 Conceptual...

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