Question

1. the diagrams below show a model airplane.

which energy transformation occurs in a rubber band powered model airplane when it is flown?
a. thermal energy stored in the rubber band is transformed into chemical energy used by the propeller.
b. kinetic energy stored in the rubber band is transformed into thermal energy used by the propeller.
c. chemical energy stored in the rubber band is transformed into potential energy used by the propeller.
d. potential energy stored in the rubber band is transformed into mechanical energy used by the propeller.

1. an incomplete energy transformation diagram is shown below.

wind turns a turbine and generates electricity. which types of energy complete this energy transformation diagram for the turbine?
a. x: solar energy, y: mechanical energy
b. x: mechanical energy, y: nuclear energy
c. x: chemical energy, y: solar energy
d. x: nuclear energy, y: chemical energy
you have reached the end of this test.

Explanation:

• For Question 19:
• When the rubber - band is wound, it has elastic potential energy. As it unwinds to power the propeller, this potential energy is converted into mechanical energy (the motion of the propeller).
• Thermal energy is related to heat, and there is no indication of heat - related energy transformation here. Kinetic energy is the energy of motion, but the rubber - band initially stores potential energy. Chemical energy is related to chemical reactions, which do not occur in this simple rubber - band - propeller system.
• For Question 20:
• Wind has kinetic energy (a form of mechanical energy as it is the energy of moving air). When wind turns a turbine, the mechanical energy of the wind (X) is converted into mechanical energy of the turbine (Y). Then the turbine is used to generate electrical energy.
• Solar energy is from the sun, nuclear energy is from nuclear reactions, and chemical energy is from chemical bonds. None of these are relevant to the wind - turbine - electrical energy transformation.

Answer:

1. D. Potential energy stored in the rubber band is transformed into mechanical energy used by the propeller.
2. A. X: solar energy, Y: mechanical energy