EOM: Thermal Energy

Aria is heating a pot of water on the stove. What type of heat transfer occurs in the water at point B?

• A. Conduction; heat rises, cold sinks

• B. Convection; heat rises, cold sinks

• C. Conduction; cold rises, heat sinks

• D. Convection; cold rises, heat sinks

Answer explanation

At point B in the pot of water, convection occurs as the heated water rises and the cooler water sinks. This process circulates heat throughout the water, making option B the correct choice.

A beach condo developer in Galveston is trying to decide what kind of windows to install in her condos. She wants the windows to provide the most comfortable environment for her renters. Which statement below is NOT a factor in choosing the windows?

• A. Windows that allow radiation from sunlight to warm the inside

• B. Windows that prevent outside air from entering via convection

• C. Windows that prevent inside air from escaping via convection

• D. Windows that block any thermal exchange

Answer explanation

Choice D is correct because blocking all thermal exchange would create an uncomfortable environment. The other options focus on managing heat and air flow, which are important for comfort.

In a science class experiment, Avery, Aria, and Rohan stacked four metal blocks of different temperatures. Where would energy transfer by conduction move downward, from a higher block to a lower block?

• Sample 2 to Sample 4

• Sample 1 to Sample 2

• Sample 3 to Sample 4

• Sample 1 to Sample 3

Answer explanation

Energy transfer by conduction occurs from a higher temperature block to a lower temperature block. Since Sample 3 is higher than Sample 4, energy will transfer from Sample 3 to Sample 4.

Benjamin conducted an experiment with four containers made of different materials, each filled with water at a temperature of 30°C. After 15 minutes, he measured the water temperature in each container. Container | Initial Temperature | Final Temperature P | 30°C | 29°C Q | 30°C | 14°C R | 30°C | 21°C S | 30°C | 9°C Which container was the most effective at preventing heat transfer from the water to the environment?

• P

• Q

• R

• S

Answer explanation

Container P had the smallest temperature drop (1°C), indicating it was the most effective at preventing heat transfer. In contrast, containers Q, R, and S lost significantly more heat, showing they were less effective insulators.

Grace and Anika heated a beaker of water to 98°C and set it on a table in their 72°C lab. They monitored the temperature of the water for 45 minutes but had to leave class when the bell rang. When they return tomorrow, what will be the temperature of the water?

• The temperature of the water will be 0°C because heat will continue to leave the beaker until it reaches freezing.

• The temperature of the water will be 72°C because once it reaches the temperature of the room, it will be at equilibrium.

• The temperature of the water will be 98°C because heat from the lab will start to warm it back up.

• The temperature of the water will be 0°C because that is the lowest temperature it can reach.

Answer explanation

The water will cool down to the lab temperature of 72°C. Once it reaches this temperature, it will be in thermal equilibrium with the surroundings, meaning it will not change further.

Noah is cooking stew over a campfire. Where is thermal energy transfer by conduction present in this scenario?

• The contact between the grill and the pot.

• The fire heating the pot.

• The heating of the lid on the pot.

• The cooking of the stew in the pot.

• The warm steam above the pot.

Answer explanation

Thermal energy transfer by conduction occurs where there is direct contact. This includes the contact between the grill and the pot, the heating of the lid on the pot, and the cooking of the stew in the pot.

Henry and Nora are learning about thermal energy in their science class. Their teacher gives them a table that lists characteristics of a simple system. Complete the chart below. Match the correct components to the appropriate location on the chart. Write the answers in the correct boxes. Fill in the correct term (Conduction, Convection, or Radiation) for each description.

• • Radiation: Thermal energy transfers through waves or rays. No matter is needed for thermal energy to travel. Ex. Energy from the Sun • Conduction: Thermal energy transfers through contact. Ex. Holding an ice pack to cool down your skin • Convection: Thermal energy transfers through a liquid or gas. Energy moves from hot, high energy to cool, low energy. Ex. Boiling rice

• • Conduction: Thermal energy transfers through waves or rays. No matter is needed for thermal energy to travel. Ex. Energy from the Sun • Radiation: Thermal energy transfers through contact. Ex. Holding an ice pack to cool down your skin • Convection: Thermal energy transfers through a liquid or gas. Energy moves from hot, high energy to cool, low energy. Ex. Boiling rice

• • Radiation: Thermal energy transfers through a liquid or gas. Energy moves from hot, high energy to cool, low energy. Ex. Boiling rice • Conduction: Thermal energy transfers through waves or rays. No matter is needed for thermal energy to travel. Ex. Energy from the Sun • Convection: Thermal energy transfers through contact. Ex. Holding an ice pack to cool down your skin

• • Convection: Thermal energy transfers through waves or rays. No matter is needed for thermal energy to travel. Ex. Energy from the Sun • Radiation: Thermal energy transfers through a liquid or gas. Energy moves from hot, high energy to cool, low energy. Ex. Boiling rice • Conduction: Thermal energy transfers through contact. Ex. Holding an ice pack to cool down your skin

Answer explanation

The correct terms are: Radiation for energy transfer through waves (e.g., Sun), Conduction for contact transfer (e.g., ice pack), and Convection for transfer in liquids/gases (e.g., boiling rice).

William is observing a cooling cup of coffee. At what time does the thermal energy transfer begin to slow down?

Answer explanation

The thermal energy transfer begins to slow down as the temperature difference between the coffee and its surroundings decreases. This occurs as the coffee approaches room temperature, reducing the rate of heat loss.

Noah investigates the thermal energy transfer of two liquids. He graphs the temperature of the liquids over time. Which statement best describes the thermal energy transfer of the liquids?

• Thermal energy from the cooler liquids is transferred to the warmer environment until the liquids reach thermal equilibrium.

• Thermal energy from the warmer liquids is transferred to the cooler environment until the liquids reach thermal equilibrium.

• Thermal energy from the environment is increasing the temperature of the liquids.

• Thermal energy from the warm liquids is decreasing the temperature of the environment.

Answer explanation

Thermal energy naturally flows from warmer to cooler areas. In this case, the warmer liquids transfer thermal energy to the cooler environment until they reach thermal equilibrium, making the second choice the correct statement.

Henry is holding a metal tumbler filled with hot coffee. How is the tumbler affected by the transfer of heat through conduction, convection, and radiation?

• The tumbler remains unaffected by all three modes of heat transfer.

• The tumbler gets heated mainly by conduction, but also by convection and radiation.

• The tumbler cools down due to heat transfer.

• The tumbler only gets heated by radiation.

Answer explanation

The tumbler gets heated mainly by conduction as it directly contacts the hot coffee. Convection occurs as the hot air around the tumbler rises, and radiation contributes as heat is emitted from the tumbler's surface.