Unit Test: OpenSciEd 6.2 Thermal Energy

Question 1

Which type of energy transfer happens when thermal energy moves through direct contact between particles, such as your warm hand warming a cold drink?

Accepted Answer

Conduction

Question 2

Ice is in a cup on a table in a warm room. What happens to the water particles in the ice as the ice melts?

Accepted Answer

They gain thermal energy and move faster.

Question 3

A class tested four cups. Each cup started with 200 mL of ice water at 2°C. After 30 minutes in the same warm room, they recorded the final temperatures. Based on this data, which cup material is the BEST insulator?

Accepted Answer

Foam

Question 4

A student heated a pot of water on a stove and recorded the temperature every 2 minutes. Figure: Temperature of Heated Water Over Time — Line graph of water temperature rising from 20°C at 0 minutes to 100°C at 8 minutes, then staying at 100°C through 12 minutes. — 0: 20 °C · 2: 40 °C · 4: 60 °C · 6: 80 °C · 8: 100 °C · 10: 100 °C · 12: 100 °C What best explains the pattern in the data after 8 minutes?

Accepted Answer

Energy is still added, but it is used to change liquid water into gas.

Question 5

A team wants to redesign a cup so a cold drink stays cold longer on a sunny day. Their first test cup had thin plastic walls, no lid, and a black outer color. Which redesign would MOST reduce thermal energy transfer into the drink?

Accepted Answer

Add a lid, use double walls with an air gap, and make the outside white.

Question 6

When a cold drink warms up on a table, thermal energy moves from the warmer surrounding air into the colder drink.

Accepted Answer

true

Question 7

As thermal energy is removed from liquid water, its particles usually move faster until the water freezes into ice.

Accepted Answer

false

Question 8

A class tested cups that each started with 200 mL of ice water. They measured the water temperature after 30 minutes. Based on this data, the foam cup was the best insulator because its water had the smallest temperature change.

Accepted Answer

true

Question 9

A student placed two identical cans of cold water in the sun for 20 minutes. One can was painted black and one was painted white. Sample results from the student's investigation: Figure: Water Temperature in Cans Left in Sunlight — Line graph showing water temperature in a black can rising from 10 to 24 degrees Celsius and in a white can rising from 10 to 15 degrees Celsius over 20 minutes. — 0 min: Black can 10 °C, White can 10 °C · 5 min: Black can 14 °C, White can 11 °C · 10 min: Black can 18 °C, White can 13 °C · 15 min: Black can 21 °C, White can 14 °C · 20 min: Black can 24 °C, White can 15 °C The data suggest that the black can absorbed more light energy from the sun by radiation than the white can.

Accepted Answer

true

Question 10

A student designs a cup to keep a drink cold. The cup has a lid, a foam layer, and a shiny outer surface. In this design, the lid mainly reduces conduction, and the shiny surface mainly reduces convection.

Accepted Answer

false

Question 11

Name the THREE ways thermal energy can be transferred. For each one, write a short definition and give one example of how it could warm up a cold drink.

Accepted Answer

Conduction is energy transfer when particles touch and collide, like a warm hand holding a cold cup. Convection is energy transfer by a moving fluid (liquid or gas), like warm air flowing around the cup. Radiation is energy transfer by light/electromagnetic waves, like sunlight shining on the cup and being absorbed.

Question 12

What is the difference between temperature and thermal energy? In your answer, describe what is happening to the particles of a substance when its temperature goes up.

Accepted Answer

Temperature measures the average kinetic energy (how fast, on average) the particles are moving. Thermal energy is the total kinetic energy of all the particles in a substance, so it depends on both temperature and the amount of matter. When temperature goes up, the particles move faster and collide more often because energy was transferred into the substance.

Question 13

A class tested four cups. Each cup held 200 mL of ice water starting at 2 °C, and the room was 24 °C. The water temperature was recorded after 30 minutes. Sample class data: Which material was the BEST insulator? Use numbers from the table to support your answer, and explain why the aluminum cup warmed the fastest.

Accepted Answer

Foam was the best insulator because its water only warmed 3 °C (from 2 °C to 5 °C), the smallest change. Aluminum warmed the most, 12 °C (2 °C to 14 °C). Aluminum is a conductor, so energy from the warmer room air transferred quickly through the cup into the cold water by conduction. Foam has trapped air pockets that slow conduction.

Question 14

A student placed 250 mL of ice water in a cup and recorded its temperature every 5 minutes in a 24 °C room. Use the graph to answer. Figure: Ice Water Temperature in a 24 °C Room — Line graph showing water temperature rising from 2 °C at 0 minutes to 20 °C at 30 minutes, rising quickly at first and then more slowly. — 0: 2 °C · 5: 8 °C · 10: 12 °C · 15: 15 °C · 20: 17 °C · 25: 19 °C · 30: 20 °C Describe the trend in the graph. Then explain which direction thermal energy was moving, and why the temperature changed more slowly near the end.

Accepted Answer

The water temperature rose from 2 °C to 20 °C over 30 minutes, rising quickly at first (6 °C in the first 5 minutes) and slowly at the end (1 °C in the last 5 minutes). Thermal energy moved from the warmer room air into the colder water. The rate slowed because the difference in temperature between the water and the room got smaller, so energy transferred more slowly. It will stop changing when the water reaches room temperature.

Question 15

Your team must design a cup that keeps a cold drink cold for as long as possible, even when it sits in the sun. Describe TWO design features you would include. For each feature, explain which type of energy transfer (conduction, convection, or radiation) it reduces and how. Then describe how you would test your cup and use the results to improve it.

Accepted Answer

Feature 1: a double wall with foam or trapped air between the layers. This reduces conduction because air and foam are insulators that slow energy transfer from the outside into the drink. Feature 2: a shiny, light-colored outside and a lid. The shiny surface reflects sunlight, reducing radiation being absorbed, and the lid stops warm air from moving over the drink, reducing convection. Test: fill my cup and a plain cup with the same amount of ice water at the same starting temperature, place both in the sun, and record temperatures every 5 minutes for 30 minutes. If my cup still warms too fast, I would add thicker insulation or a tighter lid, then test again and compare data.

Question 16

Describe the three ways thermal energy can transfer: conduction, convection, and radiation. For EACH one, give an example of how it could warm up a cold drink in a cup on a sunny day.

Accepted Answer

Conduction is when thermal energy moves between touching objects as particles bump into each other. A warm hand holding the cup transfers energy into the cup and drink. Convection is when energy moves through a moving liquid or gas. Warm air flowing around the cup carries energy to it. Radiation is energy that travels as light without touching. Sunlight shining on the cup is absorbed and warms the drink.

Question 17

Explain the difference between temperature and thermal energy. In your answer, describe what is happening to the particles of a substance when its temperature goes up.

Accepted Answer

Temperature measures how fast the particles in a substance move on average. Thermal energy is the total energy of all the moving particles, so a big pot of water at 40°C has more thermal energy than a small cup at 40°C. When temperature goes up, energy is added and the particles move faster and spread out a little more.

Question 18

A class tested how well four cups kept ice water cold. Each cup started with 200 mL of water at 2°C in a room at 24°C. Use the data table below. Which cup was the best insulator? Use the data to support your answer, and explain in terms of energy transfer WHY the metal cup warmed the most.

Accepted Answer

The foam cup was the best insulator because its water only warmed from 2°C to 5°C, a 3°C change, while the metal cup warmed 12°C. The metal cup warmed the most because metal is a good conductor. Energy moved quickly from the warmer room air through the metal and into the cold water, making its particles move faster. Energy flows from warmer to colder, so the room transferred energy into the drink.

Question 19

A student put two cans of cold soda, one painted black and one painted white, in direct sunlight. Sample data from the student's experiment is shown. Figure: Soda Can Temperature in Sunlight — Line graph showing the black can warming from 4°C to 22°C and the white can warming from 4°C to 12°C over 40 minutes. — 0: Black can 4 °C, White can 4 °C · 10: Black can 9 °C, White can 6 °C · 20: Black can 14 °C, White can 8 °C · 30: Black can 18 °C, White can 10 °C · 40: Black can 22 °C, White can 12 °C Describe the pattern in the graph. Then explain, using the ideas of absorbing and reflecting light, why the two cans warmed differently.

Accepted Answer

Both cans warmed up, but the black can warmed faster. It went from 4°C to 22°C, an 18°C increase, while the white can only went from 4°C to 12°C, an 8°C increase. This happened because dark colors absorb more of the light energy from the sun, and that energy becomes thermal energy in the can. The white can reflects more light, so less energy is absorbed and it warms slower.

Question 20

Design a cup that will keep a drink cold for as long as possible on a hot, sunny day. Describe at least THREE design features. For each feature, explain which type of energy transfer (conduction, convection, or radiation) it reduces and how. Then describe one test you would run to check whether your design works and how you would use the results to improve it.

Accepted Answer

My cup design has three features. First, it has a double wall with a foam layer between the walls. Foam is an insulator, so it slows conduction from the warm outside into the drink. Second, it has a tight-fitting lid. The lid stops warm air from moving in and mixing with the cold drink, which reduces convection. Third, the outside of the cup is shiny silver or white. This color reflects sunlight instead of absorbing it, which reduces radiation. To test my cup, I would fill it and a regular plastic cup with the same amount of ice water at the same starting temperature. I would put both in the sun and record the temperature every 10 minutes for an hour. If my cup still warmed a lot, I would add a thicker foam layer or seal the lid better. Then I would test it again.

Cup Material	Final Temperature (°C)
Thin metal	14
Plastic	9
Foam	5
Glass	11

Unit Test: OpenSciEd 6.2 Thermal Energy

Part A: Multiple Choice

Part B: True / False

Part C: Short Answer

Part D: Essay / Extended Response

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