- Two apartment mates are arguing over the potential energy of a 10 kg TV that hangs on the wall. The first person claims that the television is 2 m from the floor so its potential energy is 10 kg × 9.8 N/kg × 2 m = 196 J. The other claims that since they are on the second floor, the TV is 12 meters above the ground so the potential energy is 10 kg × ×9.8 N/kg × 12 m =1,176 J. Who is right or are they both right? How?
 A heavy bowling ball is attached to a string and hung from the ceiling so that the ball hangs at a height just a little lower than the teacher's nose. The teacher faces the ball, steps backward a few steps and draws the ball toward her until it just touches the tip of her nose. She then asks you if she will remain uninjured if she releases the bowling ball knowing it will swing away then reverse and swing back toward her nose again. How should you answer her?
- What happens to the energy “lost” to friction?
- Compare the change in potential energy between a ball that falls from 10 meters to 5 meters in height and another ball of the same mass that falls from 7 meters to 2 meters in height.
 The force of hot expanding gas from exploding gunpowder propels a cannon ball out of the barrel of a cannon. How might the cannon be modified so that the cannonball leaves at a higher speed without increasing the amount of gunpowder used?
- How much work does it take to hold a dumbbell motionless over your head for 10 s?
- Your friend brags that his ball can bounce to a higher height that it was initially dropped from. Is he telling the truth?
- Prove mathematically that objects of different mass should fall at the same rate in the absence of friction.
- A thrown ball follows a curved path called a trajectory as it first goes up and then comes down again. At what point in the trajectory does the ball have have maximum kinetic energy? At what point does it have a maximum potential energy?
 If two objects collide and one of them is initially stationary, then can both objects be stationary after impact? Can only one of them be stationary after impact? Justify your answers.
| | - A roller coaster car begins at rest at the top of the first hill. Draw a sketch of a roller coaster with a second hill where the roller coaster cannot reach the top. Draw a sketch of a different roller coaster with a second hill that the roller coaster can get over.
- Two balls are dropped, one from twice the height of the other. What is the ratio of the speeds each ball reaches when they hit the ground?
- A bowling ball and a tennis ball are dropped separately in such a way that both have the same kinetic energy when they hit the ground. Were they dropped from the same height or a different height? If the latter, which one was dropped from a higher point?
- Describe the difference between the law of energy conservation and the everyday use of the term “energy conservation.”
- From a roof, you throw three equal mass balls each with the same initial speed: one straight down at the ground; the second straight up; and the third horizontally out from the building. When each of the three balls hit the ground, which one has the most kinetic energy?
- The bumpers on cars, as well as some cars' engine compartments, are designed to collapse in a collision. Why is this a useful design?
- Which of the following energy flow diagrams might describe the path of the energy that powers the electric light in your classroom?
- nuclear energy > thermal energy > mechanical energy > electrical energy > light energy
- chemical energy > electrical energy > nuclear energy > light energy
- mechanical energy > chemical energy > electrical energy > thermal energy > light energy
- Research three energy flow diagrams that describe ways in which solar energy is converted into electrical energy.
- A hydroelectric dam is a technology for converting potential energy to electrical energy.
- What is the source of the potential energy?
- What forms does the energy take between potential energy and electrical energy?
- Research the efficiency of conversion for a hydroelectric power station
- List five ways in which food you buy in a grocery store has an "energy content" other than the actual calories your body gets from eating the food.
- How does the Sun's energy reach us?
- Is it possible to have very little power but use a lot of energy? How?
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