Thermal Energy

What happens to the kinetic energy of particles when an object is heated?

• It decreases

• It remains the same

• It increases

• It disappears

Answer explanation

When an object is heated, the kinetic energy of its particles increases. This is because heating adds energy, causing particles to move faster and collide more vigorously, thus increasing their kinetic energy.

When particles move faster and their vibrations become more intense, what happens to the temperature?

• It decreases

• It remains the same

• It increases

• It disappears.

Answer explanation

As particles move faster and vibrate more intensely, they possess more kinetic energy, which directly correlates to an increase in temperature. Therefore, the correct answer is that the temperature increases.

When thermal energy increases, what happens to particle motion?

• A) Increases

• B) Decreases

• C) Stays the same

Answer explanation

When thermal energy increases, particles gain energy and move faster. This increased motion is why the correct answer is A) Increases.

Fill in the blank: When you hold an ice cube, thermal energy is transferred from your hand to the ice cube, causing it to _______.

• A) freeze

• B) melt

• C) evaporate

Answer explanation

When you hold an ice cube, your hand transfers thermal energy to it. This energy causes the ice to absorb heat and change from solid to liquid, which is melting. Therefore, the correct answer is B) melt.

What is the relationship between particle motion and kinetic energy when thermal energy increases?

• A) Both decrease

• B) Both increase

• C) One increases, the other decreases.

Answer explanation

As thermal energy increases, particles move faster, leading to an increase in kinetic energy. Therefore, both particle motion and kinetic energy increase, making option B the correct choice.

Fill in the blank: Heat transfer occurs until objects reach the same _______.

• A) volume

• B) mass

• C) temperature

• D) density

Answer explanation

Heat transfer occurs until objects reach the same temperature, as this is the point where thermal equilibrium is achieved. Therefore, the correct answer is C) temperature.

Which method of heat transfer involves the movement of particles within a fluid?

• A) Conduction

• B) Convection

• C) Radiation

• D) Reflection

Answer explanation

Convection is the method of heat transfer that involves the movement of particles within a fluid, such as liquids and gases. In contrast, conduction occurs in solids, radiation involves electromagnetic waves, and reflection pertains to light.

What is the primary method of heat transfer in a pot of boiling water?

• A) Conduction

• B) Convection

• C) Radiation

• D) Reflection

Answer explanation

The primary method of heat transfer in a pot of boiling water is convection. As water heats up, it becomes less dense and rises, while cooler water descends, creating a circulation pattern that transfers heat throughout the pot.

Which method of heat transfer is illustrated by the arrows pointing away from the pot in the diagram?

• Conduction

• Convection

• Radiation

• Reflection

Answer explanation

The arrows pointing away from the pot indicate heat transfer through radiation, which involves the emission of energy in the form of electromagnetic waves. This is distinct from conduction and convection, which involve direct contact and fluid movement, respectively.

Which of the following is NOT an example of a conductor?

• Cookie sheet

• Aluminum foil

• Wooden spoon

• Copper pipes

Answer explanation

A wooden spoon is made of wood, which is an insulator, not a conductor. In contrast, cookie sheets, aluminum foil, and copper pipes are all materials that conduct electricity or heat.