Bennett Mechanical Test Thermodynamics and Heat 3 — Questions and Answers
Question 1: Water boils at a lower temperature on top of a high mountain because:
- Air pressure is lower at high altitude (Correct answer)
- Air is colder at high altitude
- There is less oxygen
- Water is purer at altitude
Correct answer: Air pressure is lower at high altitude
Lower atmospheric pressure lets water boil at a temperature below 212°F.
Question 2: A thermos keeps drinks hot mainly by reducing which type of heat transfer with its vacuum layer?
- Conduction and convection (Correct answer)
- Radiation only
- Combustion
- Evaporation only
Correct answer: Conduction and convection
The vacuum between walls blocks conduction and convection because there is no matter to carry heat.
Question 3: What is the change of a substance directly from solid to gas without becoming liquid called?
- Sublimation (Correct answer)
- Condensation
- Evaporation
- Freezing
Correct answer: Sublimation
Sublimation is the direct solid-to-gas transition, as seen with dry ice.
Question 4: Two identical pots of water are heated, one covered with a lid. Which boils faster?
- The covered pot (Correct answer)
- The uncovered pot
- Both boil at the same time
- Neither will boil
Correct answer: The covered pot
A lid traps heat and reduces heat loss by evaporation, so the covered pot boils faster.
Question 5: Which material would make the best insulator to keep a house warm?
- Fiberglass batting (Correct answer)
- Copper sheeting
- Aluminum foil layers alone
- Solid steel panels
Correct answer: Fiberglass batting
Fiberglass traps air pockets that slow heat transfer, making it a good insulator.
Question 6: When you rub your hands together quickly, they get warm because:
- Friction converts mechanical energy into heat (Correct answer)
- Your blood pressure rises
- The air cools your skin
- Static electricity heats the skin
Correct answer: Friction converts mechanical energy into heat
Friction between surfaces transforms motion into thermal energy.
Question 7: Heat always flows naturally from:
- A hotter object to a cooler object (Correct answer)
- A cooler object to a hotter object
- Larger objects to smaller objects
- Lighter objects to heavier objects
Correct answer: A hotter object to a cooler object
Heat spontaneously moves from high temperature to low temperature until equilibrium.
Bennett Mechanical Test Thermodynamics and Heat 3
Water boils at a lower temperature on top of a high mountain because: