Unit 3 - Energy Transfers 1

What is one way energy can be transferred?

• By reflection

• By conduction

• By evaporation

• By filtration

Answer explanation

Energy can be transferred by conduction, which involves the direct transfer of heat through materials when they are in contact. This is different from reflection, evaporation, or filtration, which do not primarily transfer energy.

Which type of energy is NOT mentioned as a store of energy?

• Solar

• Kinetic

• Nuclear

• Chemical

Answer explanation

Solar energy is primarily harnessed from sunlight and is not typically classified as a store of energy like kinetic, nuclear, or chemical energy, which can be stored and converted into usable forms.

What does the efficiency of a system represent?

• The total energy input

• The amount of energy wasted

• The speed of energy transfer

• The ratio of useful energy output to total energy supplied

Answer explanation

The efficiency of a system represents the ratio of useful energy output to total energy supplied. This indicates how well the system converts input energy into useful work, minimizing waste.

What is conduction primarily associated with?

• Vacuum

• Solids and liquids

• Fluids

• Gases

Answer explanation

Conduction is primarily associated with solids and liquids, as it involves the transfer of heat through direct contact of particles. In gases and vacuums, conduction is less effective due to the larger distances between particles.

What happens to particles in a fluid when it is heated?

• They become denser

• They move closer together

• They stop moving

• They expand and become less dense

Answer explanation

When a fluid is heated, its particles gain energy and move faster, causing them to expand. This expansion results in a decrease in density, making the fluid less dense overall.

Which of the following is a good conductor of heat?

• Wood

• Plastic

• Metal

• Glass

Answer explanation

Metal is a good conductor of heat due to its free electrons that facilitate the transfer of thermal energy. In contrast, wood, plastic, and glass are insulators and do not conduct heat well.

What is a Sankey diagram used for?

• To show chemical reactions

• To measure temperature

• To represent energy transfer

• To calculate efficiency

Answer explanation

A Sankey diagram is specifically designed to represent energy transfer, illustrating how energy flows from one process to another. This makes it the correct choice among the options provided.

What is the main characteristic of thermal insulators?

• They transfer heat quickly

• They are usually metals

• They conduct electricity well

• They reduce unwanted energy transfer

Answer explanation

The main characteristic of thermal insulators is that they reduce unwanted energy transfer, preventing heat from escaping or entering, which is essential for maintaining temperature.

What is the process of energy transfer in fluids called?

• Conduction

• Convection

• Radiation

• Insulation

Answer explanation

The process of energy transfer in fluids is called convection. It involves the movement of fluid, which carries heat energy from one place to another, unlike conduction (solid) or radiation (through space).

Which of the following is an example of energy transfer by radiation?

• A hot air balloon rising

• A metal rod getting hot

• A lamp emitting light

• Heating water on a stove

Answer explanation

Energy transfer by radiation occurs when energy is emitted as electromagnetic waves. A lamp emitting light is a clear example, as it radiates energy in the form of light, unlike the other options which involve conduction or convection.