Exam 4 Target 7 Retake Preap 16-17
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- 1.
If mechanical energy is conserved in a system, the energy at any point in time can be in the form of
- A.
A. kinetic energy.
- B.
B. gravitational potential energy.
- C.
C. elastic potential energy.
- D.
D. all of the above
Correct Answer
D. D. all of the aboveExplanation
If mechanical energy is conserved in a system, it means that the total amount of mechanical energy remains constant over time. This implies that the energy at any point in time can be in the form of kinetic energy, which is the energy of motion, or gravitational potential energy, which is the energy stored in an object due to its position in a gravitational field, or elastic potential energy, which is the energy stored in a stretched or compressed elastic object. Therefore, all of these forms of energy can exist simultaneously in a system where mechanical energy is conserved.Rate this question:
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- 2.
Which of the following is not a form of mechanical energy?
- A.
A. kinetic energy
- B.
B. chemical potential energy
- C.
C. gravitational potential energy
- D.
D. elastic potential energy
Correct Answer
B. B. chemical potential energyExplanation
Chemical potential energy is not a form of mechanical energy because it is associated with the potential energy stored in the chemical bonds of a substance. Mechanical energy, on the other hand, refers to the energy possessed by an object due to its motion or position. Kinetic energy is the energy of motion, gravitational potential energy is the energy stored in an object due to its position in a gravitational field, and elastic potential energy is the energy stored in a stretched or compressed object.Rate this question:
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- 3.
Which of the following is a true statement about the conservation of energy?
- A.
A. Potential energy is always conserved.
- B.
B. Kinetic energy is always conserved.
- C.
C. Mechanical energy is always conserved.
- D.
D. Total energy is always conserved.
Correct Answer
D. D. Total energy is always conserved.Explanation
The statement "Total energy is always conserved" is true because according to the law of conservation of energy, energy cannot be created or destroyed, it can only be transferred or transformed from one form to another. Therefore, the total amount of energy in a closed system remains constant. This means that the sum of potential energy and kinetic energy, also known as mechanical energy, is conserved. Additionally, other forms of energy such as thermal energy, electrical energy, or chemical energy can also be converted into one another, but the total energy remains the same.Rate this question:
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- 4.
Friction converts kinetic energy to
- A.
A. mechanical energy.
- B.
B. nonmechanical energy.
- C.
C. potential energy.
- D.
D. total energy.
Correct Answer
B. B. nonmechanical energy.Explanation
Friction is a force that opposes motion and causes energy to be lost in the form of heat. As an object moves against a surface, the friction between them converts some of the object's kinetic energy into thermal energy, which is a form of nonmechanical energy. Therefore, the correct answer is b. nonmechanical energy.Rate this question:
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- 5.
Why doesn’t the principle of mechanical energy conservation hold in situations when frictional forces are present?
- A.
A. Kinetic energy is not completely converted to a form of potential energy.
- B.
B. Potential energy is completely converted to a form of gravitational energy.
- C.
C. Chemical energy is not completely converted to electrical energy.
- D.
D. Kinetic energy is completely converted to a form of gravitational energy.
Correct Answer
A. A. Kinetic energy is not completely converted to a form of potential energy.Explanation
When frictional forces are present, some of the mechanical energy is converted into heat energy due to the work done against friction. This means that not all of the kinetic energy is converted into potential energy. Therefore, the principle of mechanical energy conservation does not hold in these situations.Rate this question:
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