1. When a scientist is asked to evaluate the efficiency of a new engine, why is it insufficient to only measure the kinetic energy it produces?
- A. Because this approach ignores the energy lost as heat and sound.
- B. Because kinetic energy is a theoretical value and cannot be measured.
- C. Because the cost of fuel is the most important factor in efficiency.
- D. Because the engine's speed might change during the measurement.
2. In most mechanical and electrical systems, energy is inevitably wasted and does not contribute to the useful output. What are the two most common forms of this wasted energy?
- A. Light and chemical energy
- B. Potential and nuclear energy
- C. Thermal and sound energy
- D. Magnetic and electrical energy
3. According to the Law of Conservation of Energy, what is the fundamental relationship between the total energy put into a closed system and the total energy accounted for after a process occurs?
- A. The total energy output is always less than the total energy input because some energy is destroyed by friction.
- B. The total energy output can be made greater than the energy input with a sufficiently advanced design.
- C. The total energy accounted for as output, including all forms like heat and sound, is exactly equal to the total energy input.
- D. Energy input and energy output are independent variables that do not have a predictable relationship.
4. In a real-world mechanical system like a bicycle, why is the useful kinetic energy that moves the bike forward always less than the chemical energy the rider expends?
- A. The rider intentionally holds back to conserve energy for later.
- B. Some of the rider's energy is converted into non-useful forms, primarily heat due to friction in the gears and sound.
- C. Energy is destroyed by the force of air resistance acting on the rider.
- D. The bicycle's frame absorbs and stores a significant portion of the energy input.
5. An inventor claims to have built a flashlight that, after being cranked once, will produce light indefinitely without any additional energy input. Why is this claim scientifically invalid?
- A. The claim violates the Law of Conservation of Energy because a system cannot output more energy than it receives.
- B. A single crank cannot possibly store enough energy in a battery to power a modern LED light bulb.
- C. It is impossible for mechanical energy to be converted into light energy.
- D. The materials used to build such a device would be too heavy to be practical.