- Compare water flowing in a hose to electricity. Pressure in the pipe causes water to flow through the hose. What electrical quantity acts like pressure and causes electrical current to flow?
- Which is the correct statement about a 12 V battery?
- 12 amps of electrical current can flow from the battery.
- Each amp of electrical current that flows carries 12 watts of power.
- The battery contains 12 times as much stored energy as a 1 volt battery.
 Explain why moving a light source three times farther away reduces the intensity of light by a factor of nine − the light gets nine times dimmer.
- Describe the energy transformations that a pole vaulter uses to clear the bar.
 You are about to pour cold water into one cup and hot water into a second cup. Is there any way that you can put the same amount of thermal energy into each cup?
- More than a century ago, it was common for people to use hot water bottles to heat the sheets in their beds before climbing in. Why didn't they use hot metal objects of similar mass instead?
- Which is a larger change in temperature, 1°F or 1°C?
 Compare a 20 kg block of ice to a 200 g cup of hot tea.
- Which one has more thermal energy? Why?
- If you poured the hot tea into an indentation on the top of the ice block, would you expect the ice to melt or the tea to cool to the freezing point? Why?
- Areas of the world that are close to oceans or other large bodies of waters usually have climates that have less range in temperature (both high and low). Why is this so?
- When you heat a flask of water, how are you changing the ordered kinetic energy of the water molecules? How are you changing the random kinetic energy of the water molecules?
- A small airplane has a kinetic energy of 5,000,000 J when it travels at 100 m/s. What is its mass?
- A 1 kg ball and a 9 kg ball have the same Ek. Compare their speeds.
- If you double the speed and mass of an object how does its kinetic energy change?
| | - How much work do you do when you push a 400 kg car for 6 m with a force of 300 N? What is the car's final speed if all your work became kinetic energy?
- How much distance does it take to stop a car going 30 m/s (67 mph) if the brakes can apply a force equal to one half the car's weight?
- A mobile that weighs 28 N is hanging from a 5 m high ceiling by a 2 m high string. What is its potential energy with respect to the ground, the ceiling and a point at the same height as the mobile?
- A 5 kg ball is at a height of 10 m. How much work is required to move it to a height of 35 m?
- At what height would a 15 kg bird have a potential energy of 2400 J?
- How much total mechanical energy does a plane with mass of 1,000 kg have when it moves at 235 m/s at an altitude of 2 km?
- What is the kinetic energy of a 6 kg bird moving at a speed of 15 m/s?
- You can only apply a 200 N force but you need to make a 20 kg wagon of mulch travel at a speed of 10 m/s. How far do you have to push the wagon before its speed reaches 10 m/s if it starts from rest? You may assume no friction.
- Consider a rubber ball which has an efficiency in one bounce of 80%. That means 80% of the kinetic energy before the bounce remains kinetic energy after the bounce. (The rest of the energy is converted to thermal energy.)
- If the ball drops from a height of 5 meters, how high does it bounce back on the first bounce?
- How high does the ball bounce on the second, third, and fourth bounces?
- A 60 kg diver drops from a ledge that is 50 feet above the water. What is the speed of the diver upon hitting the water? Give your answer in m/s and mph.
- A 10,000 kg railroad car traveling north at 10 m/s collides with a 5,000 kg rail car also moving north but at an unknown speed. After the collision, the two cars lock together and move north at 8 m/s. How fast was the second car moving before the impact?
- A 2,000 kg car moving at 10 m/s collides head-on with a 2,500 kg car moving in the opposite direction at 15 m/s. The two cars are locked together after impact.
- Is this an elastic or an inelastic collision? Why?
- What is the speed of the cars after impact?
- Calculate the kinetic energies of the cars, both before and after impact.
- What fraction of the kinetic energy was lost during the impact? Where did the energy go?
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