L3: Understanding Thermal Energy (7.8A)

Describe the relationship between temperature and the kinetic energy of particles in a substance. How does this relationship affect the state of matter of the substance?

• As temperature increases, kinetic energy decreases, causing the substance to solidify.

• As temperature increases, kinetic energy increases, which can cause the substance to change from solid to liquid to gas.

• As temperature decreases, kinetic energy increases, causing the substance to melt.

• Temperature and kinetic energy are unrelated, and do not affect the state of matter.

Answer explanation

As temperature increases, particles move faster, increasing their kinetic energy. This can lead to changes in state, such as solid to liquid (melting) or liquid to gas (vaporization), making the correct choice accurate.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

Explain how thermal equilibrium is achieved between two substances of different temperatures within a closed system.

• Thermal energy moves from the cooler substance to the warmer substance until both reach the same temperature.

• Thermal energy moves from the warmer substance to the cooler substance until both reach the same temperature.

• Thermal energy remains constant in both substances, maintaining their initial temperatures.

• Thermal energy is transferred equally in both directions, maintaining a temperature difference.

Answer explanation

Thermal equilibrium is achieved when thermal energy moves from the warmer substance to the cooler one. This transfer continues until both substances reach the same temperature, making the correct choice the second option.

Tags

NGSS.MS-PS3-4

NGSS.MS-PS3-5

Illustrate and explain the process of conduction and how it differs from convection and radiation.

• Conduction involves the transfer of thermal energy through electromagnetic waves, unlike convection and radiation.

• Conduction involves the transfer of thermal energy through the movement of fluids, unlike convection and radiation.

• Conduction involves the transfer of thermal energy through direct contact between particles, unlike convection and radiation.

• Conduction involves the transfer of thermal energy through the vacuum of space, unlike convection and radiation.

Answer explanation

Conduction is the transfer of thermal energy through direct contact between particles, as seen in solids. In contrast, convection involves fluid movement, and radiation transfers energy through electromagnetic waves.

Tags

NGSS.MS-PS3-4

Analyze a scenario where a metal spoon is placed in a hot cup of coffee. Which type of thermal energy transfer is primarily responsible for the spoon becoming hot?

• Conduction

• Convection

• Radiation

• None of the above

Answer explanation

The spoon becomes hot due to conduction, which is the transfer of thermal energy through direct contact. The heat from the hot coffee is transferred to the spoon, making it warm.

A pot of water is heated on a stove. Describe the process of convection that occurs within the pot and how it contributes to the heating of the water.

• Convection occurs as heat is transferred through electromagnetic waves, heating the water evenly.

• Convection occurs as heat is transferred through direct contact, heating only the bottom layer of water.

• Convection occurs as warmer water rises and cooler water sinks, creating a circulation that heats the water evenly.

• Convection does not occur in this scenario; only conduction and radiation are involved.

Answer explanation

Convection in the pot occurs as warmer water, heated from the bottom, rises while cooler water sinks. This creates a circulation pattern that distributes heat evenly throughout the water, making the correct choice the one that describes this process.

Tags

NGSS.MS-PS3-5

Differentiate between conduction, convection, and radiation by classifying the following scenario: The warmth felt from the sun on a sunny day.

• Conduction

• Convection

• Radiation

• None of the above

Answer explanation

The warmth felt from the sun is due to radiation, which is the transfer of heat through electromagnetic waves. Unlike conduction and convection, radiation does not require a medium to travel, allowing heat from the sun to reach us in space.

Evaluate the following scenario: A heater warms a room by circulating warm air. Which type of thermal energy transfer is primarily involved?

• Conduction

• Convection

• Radiation

• None of the above

Answer explanation

The heater warms the room by circulating warm air, which is a process of convection. Convection involves the movement of fluid (air) to transfer heat, making it the primary type of thermal energy transfer in this scenario.

Describe how thermal energy is transferred through radiation and provide an example of this process in everyday life.

• Thermal energy is transferred through direct contact, such as touching a hot stove.

• Thermal energy is transferred through the movement of fluids, such as boiling water.

• Thermal energy is transferred through electromagnetic waves, such as the heat from the sun warming your skin.

• Thermal energy is transferred through sound waves, such as hearing a loud noise.

Answer explanation

Thermal energy is transferred through electromagnetic waves, which do not require a medium. An everyday example is the sun's heat warming your skin, demonstrating radiation transfer.

Tags

NGSS.MS-PS1-4

Analyze the process of thermal energy transfer in a scenario where a person is sitting by a campfire. Which types of thermal energy transfer are involved?

• Only conduction

• Only convection

• Only radiation

• Both convection and radiation

Answer explanation

In this scenario, thermal energy is transferred from the campfire to the person through both convection (warm air rising) and radiation (infrared heat emitted by the fire). Thus, the correct answer is both convection and radiation.

Match each prompt with the correct response

• Occurs in all objects that absorb heat

• Poor conductors

• Good insulators

• Radiation

• Poor insulators

• Good conductors