Thermal Energy Worksheet Answer Key: Quick Solutions!
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Thermal energy is a fundamental concept in physics that deals with the heat and energy associated with the temperature of matter. Understanding thermal energy is essential for students across various educational levels, especially in science classes. In this article, we will delve into some quick solutions and insights regarding a Thermal Energy Worksheet and provide an answer key to common problems that you might encounter.
Understanding Thermal Energy
What is Thermal Energy? 🔥
Thermal energy refers to the total kinetic energy of the particles in a substance. When the particles of a material move faster, the thermal energy increases, resulting in a higher temperature. Understanding this concept is crucial when solving problems in thermal energy worksheets.
Key Formulas to Know
To tackle problems related to thermal energy effectively, it’s essential to familiarize yourself with the key formulas:
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Q = mcΔT
Where:- Q = heat energy (in joules)
- m = mass (in kilograms)
- c = specific heat capacity (in J/kg°C)
- ΔT = change in temperature (in °C)
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Q = mL
Where:- L = latent heat (in J/kg), applicable for phase changes.
Common Units of Measurement
| Quantity | Unit |
|---|---|
| Heat Energy | Joules (J) |
| Mass | Kilograms (kg) |
| Temperature | Degrees Celsius (°C) |
| Specific Heat | J/(kg°C) |
| Latent Heat | J/kg |
Quick Solutions to Common Problems
Problem 1: Calculating Heat Energy for a Temperature Change
Question: How much thermal energy is needed to raise the temperature of 2 kg of water from 20°C to 100°C? (Specific heat capacity of water is 4,186 J/kg°C)
Solution:
Using the formula Q = mcΔT:
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Identify values:
- m = 2 kg
- c = 4,186 J/kg°C
- ΔT = 100°C - 20°C = 80°C
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Plug values into the formula:
- Q = 2 kg × 4,186 J/kg°C × 80°C = 668,960 J
Problem 2: Calculating Heat Energy for Phase Change
Question: If 1.5 kg of ice at 0°C is converted into water at 0°C, how much heat energy is absorbed? (Latent heat of fusion for ice is 334,000 J/kg)
Solution:
Using the formula Q = mL:
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Identify values:
- m = 1.5 kg
- L = 334,000 J/kg
-
Plug values into the formula:
- Q = 1.5 kg × 334,000 J/kg = 501,000 J
Important Notes on Thermal Energy
"Always remember that thermal energy can be transferred in three ways: conduction, convection, and radiation. Understanding these processes can help in solving real-life thermal energy problems."
Problem 3: Cooling and Heat Loss
Question: If a 0.5 kg metal block at 150°C cools down to 25°C, how much heat is lost? (Specific heat capacity of the metal is 500 J/kg°C)
Solution:
-
Identify values:
- m = 0.5 kg
- c = 500 J/kg°C
- ΔT = 150°C - 25°C = 125°C
-
Plug values into the formula:
- Q = 0.5 kg × 500 J/kg°C × 125°C = 31,250 J
Problem 4: Insulation and Heat Transfer
Question: Calculate the heat loss for a house insulated by materials with an R-value of 30, given a temperature difference of 20°C across the walls. Assume the surface area of the wall is 100 m².
Solution:
-
Use the formula for heat transfer:
Q = (ΔT × Area) / R -
Identify values:
- ΔT = 20°C
- Area = 100 m²
- R = 30
-
Plug values into the formula:
- Q = (20°C × 100 m²) / 30 = 66.67 J/s
Practice Problems for Students
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Problem 1: A 3 kg object is heated from 25°C to 75°C. If the specific heat capacity is 3,000 J/kg°C, calculate the heat absorbed.
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Problem 2: Determine the heat needed to convert 2 kg of water at 100°C into steam. (Latent heat of vaporization for water is 2,250,000 J/kg)
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Problem 3: A 4 kg aluminum block cools from 150°C to 30°C. What is the heat lost? (Specific heat capacity of aluminum is 900 J/kg°C)
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Problem 4: If a 0.8 kg block of ice melts at 0°C, how much heat is absorbed? (Latent heat of fusion for ice is 334,000 J/kg)
Conclusion
Thermal energy is a vital topic that forms the basis for understanding how heat and energy are transferred in various materials and environments. By familiarizing yourself with the key concepts, formulas, and common problems associated with thermal energy, you will be well-equipped to tackle worksheets and examinations on this topic. Always remember that practice is essential, so make sure to work through various problems to master this subject!