Thermal Physics Practice Questions

IB (International Baccalaureate) · IB Physics HL · 147 free MCQs with instant results and detailed explanations.

147
Total
47
Easy
70
Medium
30
Hard

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Sample Questions from Thermal Physics

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Q1
Easy
What is the main principle behind the operation of a heat engine?
A. Conversion of thermal energy into mechanical work
B. Conversion of mechanical work into thermal energy
C. Complete conversion of energy with no losses
D. Absorption of heat from a sink only
Show Answer & Explanation
Correct Answer: A
A heat engine works by converting thermal energy from a heat source into mechanical work, which is the essence of its operation.
Q2
Easy
If 200 J of heat is added to an ideal gas at constant volume, what is the change in internal energy?
A. 0 J
B. 100 J
C. 200 J
D. 400 J
Show Answer & Explanation
Correct Answer: C
For an ideal gas at constant volume, the change in internal energy is equal to the heat added. Therefore, the change in internal energy is 200 J.
Q3
Easy
Which of the following statements about thermal conduction is true?
A. It requires the movement of the material
B. It occurs in fluids only
C. It involves the transfer of kinetic energy between particles
D. It is the slowest mode of heat transfer
Show Answer & Explanation
Correct Answer: C
Thermal conduction involves the transfer of kinetic energy between adjacent particles in a solid. This process does not require the bulk movement of the material.
Q4
Medium
A 200 g block of metal is heated from 20ยฐC to 100ยฐC. If the specific heat capacity of the metal is 0.45 J/gยฐC, how much heat energy is absorbed by the block?
A. 7200 J
B. 3600 J
C. 5400 J
D. 9000 J
Show Answer & Explanation
Correct Answer: C
The heat energy absorbed is calculated using the formula Q = mcฮ”T, where m is the mass, c is the specific heat capacity, and ฮ”T is the change in temperature. Here, Q = 200 g ร— 0.45 J/gยฐC ร— (100ยฐC - 20ยฐC) = 5400 J.
Q5
Medium
A gas expands isothermally at a temperature of 300 K from a volume of 2.0 L to 5.0 L. If the pressure of the gas initially is 1.0 atm, what is the final pressure of the gas?
A. 0.4 atm
B. 0.6 atm
C. 0.8 atm
D. 1.5 atm
Show Answer & Explanation
Correct Answer: A
According to Boyle's law, for an isothermal process, P1V1 = P2V2. Rearranging gives P2 = P1V1/V2. Here, P2 = 1.0 atm ร— 2.0 L / 5.0 L = 0.4 atm.
Q6
Medium
In a specific heat experiment, a container holding 500 g of water at 25ยฐC is heated until it reaches a final temperature of 60ยฐC. If the amount of heat added is 17,500 J, what is the specific heat capacity of water used in this experiment?
A. 2.5 J/gยฐC
B. 4.0 J/gยฐC
C. 3.0 J/gยฐC
D. 5.0 J/gยฐC
Show Answer & Explanation
Correct Answer: B
Using the formula Q = mcฮ”T, we rearranged it to find c = Q / (mฮ”T). Here, ฮ”T = 60ยฐC - 25ยฐC = 35ยฐC. Thus, c = 17500 J / (500 g ร— 35ยฐC) = 4.0 J/gยฐC.
Q7
Medium
A 10 kg object at 20ยฐC is placed in an insulated container with 5 kg of ice at 0ยฐC. Assuming no heat loss to the surroundings, what is the final equilibrium temperature when the ice melts completely and the object reaches thermal equilibrium?
A. 0ยฐC
B. 5ยฐC
C. 10ยฐC
D. 15ยฐC
Show Answer & Explanation
Correct Answer: C
The heat lost by the object will equal the heat gained by the ice. The specific heat of water is 4.2 J/gยฐC. The heat lost by the object will melt the ice and then raise the temperature of the resultant water to 10ยฐC, based on energy conservation.
Q8
Hard
A block of ice at 0ยฐC is placed in a calorimeter containing 200 g of water at 80ยฐC. If the specific heat capacity of water is 4.18 J/gยฐC and the latent heat of fusion of ice is 334 J/g, what will be the final temperature of the system when thermal equilibrium is reached? Assume no heat is lost to the surroundings.
A. 30ยฐC
B. 25ยฐC
C. 20ยฐC
D. 15ยฐC
Show Answer & Explanation
Correct Answer: B
To find the final temperature, we set the heat lost by water equal to the heat gained by ice. Calculating the heat lost by the water as it cools from 80ยฐC to the final temperature involves using q = mcฮ”T, and the heat gained by the ice includes both melting and warming up. By solving these equations, we find that the final equilibrium temperature is 25ยฐC.
Q9
Hard
A gas expands isothermally at a temperature of 300 K from a volume of 2.0 L to 5.0 L. If the initial pressure of the gas is 4.0 atm, what is the work done by the gas during this expansion? (Use R = 8.31 J/(molยทK) for calculations.)
A. 108.6 J
B. 96.0 J
C. 87.2 J
D. 54.6 J
Show Answer & Explanation
Correct Answer: A
The work done on/by the gas during an isothermal process can be calculated using the formula W = nRT ln(V_final/V_initial). Here, we need to first convert pressure to moles using the ideal gas law. After substituting values and calculating, we find the work done is approximately 108.6 J.
Q10
Hard
A 1 kg block of ice at -10ยฐC is placed in 500 g of water at 20ยฐC. Assuming no heat is lost to the surroundings, what will be the final temperature of the system once thermal equilibrium is reached? (Specific heat of ice = 2.1 J/gยฐC, specific heat of water = 4.18 J/gยฐC, latent heat of fusion of ice = 334 J/g)
A. 0ยฐC
B. 10ยฐC
C. 5ยฐC
D. 15ยฐC
Show Answer & Explanation
Correct Answer: C
The final temperature is 5ยฐC as the heat lost by the water is equal to the heat gained by the ice, including the energy needed to melt the ice at 0ยฐC.

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Thermal Physics โ€” IB (International Baccalaureate) IB Physics HL Practice Questions Online

This page contains 147 practice MCQs for the chapter Thermal Physics in IB (International Baccalaureate) IB Physics HL. The questions are organized by difficulty โ€” 47 easy, 70 medium, 30 hard โ€” so you can choose the right level for your preparation.

Every question includes a detailed explanation to help you understand the concept, not just memorize answers. Take a timed quiz to simulate exam conditions, or practice at your own pace with no time limit.