Thermal Energy and Equilibrium — Worksheet Extraction

Lotti is enjoying a cup of hot chocolate outside on a cool day and wants to investigate how the 10°C air affects the temperature of her drink. She measures the temperature of the hot chocolate at different intervals until the temperature stops changing. Describe what is happening to thermal energy and what the resulting temperature of her drink is.

• Thermal energy moves from the air to the hot chocolate until the final temperature of the chocolate is 10°C.

• Thermal energy moves from the hot chocolate to the air until the final temperature of the chocolate is 5°C.

• Thermal energy moves from the air to the hot chocolate until the final temperature of the chocolate is 25°C.

• Thermal energy moves from the hot chocolate to the air until the final temperature of the chocolate is 10°C.

Answer explanation

Thermal energy transfers from the hot chocolate to the cooler air, causing the drink's temperature to decrease until it reaches thermal equilibrium at 10°C, the temperature of the surrounding air.

Tags

NGSS.MS-PS1-4

A student is baking a cake at home. He mixes together all the ingredients and puts the batter into a hot oven. The batter ______ thermal energy until the batter and the air in the oven are the same ______. Once this occurs, __________________________ has been reached. Which of the terms best complete the paragraph?

• loses; mass; thermal energy

• gains; temperature; thermal equilibrium

• gains; state of matter; conduction

• loses; temperature; thermal equilibrium

Answer explanation

The batter gains thermal energy as it heats up in the oven. This process continues until the batter and the air reach the same temperature, indicating that thermal equilibrium has been achieved.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

A student is conducting two different investigations to test how thermal energy is transferred when equal amounts of liquid at different temperatures are poured into two different sides of the same container. The two sides are separated from each other by aluminum foil. The conditions for the two investigations are below. Investigation A: Liquid 1 is 70°C and Liquid 2 is 50°C. Investigation B: Liquid 1 is 20°C and Liquid 2 is 90°C. In which investigation will the liquids reach thermal equilibrium first, and why?

• Investigation A; Since the temperatures are closer together, less thermal energy will move from the warm water to the cool water. It will take less time to transfer less energy.

• Investigation A; Since the temperatures are closer together, less thermal energy will move from the cool water to the warm water. It will take less time to transfer less energy.

• Investigation B; Since the temperatures are farther apart, more thermal energy will move from the warm water to the cool water. It will take less time to transfer more energy.

• Investigation B; Since the temperatures are farther apart, less energy will move from the cool water to the warm water. It will take less time to transfer less energy.

Answer explanation

Investigation A will reach thermal equilibrium first because the temperatures of the liquids are closer together. This results in less thermal energy needing to be transferred, allowing for a quicker equilibrium.

Tags

NGSS.MS-PS3-4

NGSS.MS-PS3-3

Look at the image of the liquid and the block. What will happen when the block is placed into the liquid?

• Energy will transfer from the liquid to the block because thermal energy moves from warmer temperatures to cooler temperatures.

• Energy will transfer from the liquid to the block because thermal energy moves from more massive substances to less massive substances.

• Energy will transfer from the block to the liquid because thermal energy moves from cooler temperatures to warmer temperatures.

• Energy will transfer from the block to the liquid because thermal energy moves from more massive substances to less massive substances.

Answer explanation

When the block is placed in the liquid, thermal energy transfers from the warmer liquid to the cooler block, as energy moves from higher to lower temperatures.

Tags

NGSS.MS-PS1-4

The image shows an investigation that used ice cubes placed on two different blocks at different time intervals. How is thermal energy being transferred during each time interval, and how does this differ between the two blocks?

Answer explanation

Thermal energy is transferred from the blocks to the ice cubes through conduction. The block with higher thermal conductivity will transfer energy more efficiently, causing the ice to melt faster compared to the other block.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

A classmate is investigating how energy is transferred when a cold pack is used on a person’s body. The setup shows a cold pack placed on skin, and the table below records temperatures over time. Predict what the temperature of the person's skin and the cold pack will be after 15 minutes and beyond. Explain your reasoning using evidence from the investigation and your knowledge of thermal energy transfer.

Answer explanation

After 15 minutes, the cold pack will be warmer, and the skin temperature will decrease. Energy transfers from the skin to the cold pack, cooling the skin and warming the pack until thermal equilibrium is approached.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

NGSS.MS-PS3-3