1.
What two forms of energy combine to make mechanical energy?
Correct Answer
D. Kinetic andPotential
Explanation
Kinetic and potential energy are the two forms of energy that combine to make mechanical energy. Kinetic energy is the energy of motion, while potential energy is the energy stored in an object due to its position or condition. In mechanical systems, objects can have both kinetic and potential energy simultaneously. For example, a moving car has kinetic energy, while a stretched spring has potential energy. When these two forms of energy combine, they contribute to the overall mechanical energy of the system.
2.
What type of energy is produced and wasted during most energy transformations?
Correct Answer
B. Thermal
Explanation
During most energy transformations, thermal energy is both produced and wasted. Energy transformations involve the conversion of one form of energy to another, such as the conversion of chemical energy to thermal energy in combustion reactions or the conversion of electrical energy to thermal energy in electrical appliances. Thermal energy is often lost as waste heat during these transformations, as it is difficult to fully utilize or capture all the energy produced. Therefore, thermal energy is the type of energy that is both produced and wasted during most energy transformations.
3.
You notice after you walk across a room, you feel a spark when you touch the doorknob. What energy transformation must have taken place?
Correct Answer
B. Mechanical --> electrical
Explanation
When you walk across a room, friction is created between your shoes and the floor. This friction causes the build-up of static electricity on your body. When you touch the doorknob, the excess electrons from your body flow to the doorknob, creating an electrical discharge or spark. Therefore, the energy transformation that must have taken place is from mechanical energy (walking) to electrical energy (spark).
4.
In what state is chemical energy always in?
Correct Answer
B. Potential
Explanation
Chemical energy is always in a potential state. This is because chemical energy is stored within the bonds of molecules and can be released or converted into other forms of energy, such as kinetic energy, when those bonds are broken. Thus, potential energy refers to the stored energy within a system, in this case, chemical energy.
5.
What energy transformation takes place when something burns?
Correct Answer
A. Chemical --> thermal
Explanation
When something burns, a chemical reaction called combustion occurs. This reaction releases stored chemical energy in the form of heat, light, and sometimes sound. This energy transformation is from chemical energy to thermal energy, as the burning substance undergoes a chemical change and produces heat as a result.
6.
What energy tranformation happens in a toaster?
Correct Answer
A. Mechanical --> electrical
Explanation
In a toaster, the energy transformation that occurs is from mechanical energy to electrical energy. This is because when the toaster is turned on, the user pushes down the lever which activates a mechanical switch. This mechanical energy is then converted into electrical energy, which powers the heating elements inside the toaster. The electrical energy is then transformed into thermal energy, which is used to toast the bread. Therefore, the correct answer is mechanical to electrical.
7.
When a turbine rotates to produce electricity what energy transformation takes place?
Correct Answer
D. Mechanical --> electrical
Explanation
When a turbine rotates, it converts the mechanical energy of the rotating blades into electrical energy. This transformation occurs as the rotating motion of the turbine spins a generator, which uses the principles of electromagnetic induction to produce electricity. Therefore, the energy transformation that takes place is from mechanical energy to electrical energy.
8.
Wind has energy because
Correct Answer
B. It can do work.
Explanation
Wind has energy because it can do work. This is because wind is the movement of air molecules, and this movement can be harnessed to perform tasks or create power. Wind turbines, for example, convert the kinetic energy of the wind into mechanical energy, which can then be used to generate electricity. The ability of wind to do work is what makes it a valuable source of renewable energy.
9.
The ability to do work or cause change is called _________.
Correct Answer
A. Energy
Explanation
Energy is the correct answer because it is the capacity or ability to do work or cause change. It can exist in various forms such as kinetic, potential, thermal, and chemical energy. Energy is required for any kind of work to be done or for any change to occur in a system.
10.
When you stretch a rubber band, you give it _______.
Correct Answer
B. Elastic potenital energy.
Explanation
When you stretch a rubber band, you give it elastic potential energy. This is because the rubber band stores energy in the form of potential energy when it is stretched. The potential energy is stored in the stretched bonds between the rubber molecules, and when released, this energy is converted back into kinetic energy as the rubber band returns to its original shape.