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Question
A gas in a closed container is heated with 10 J of energy, causing the lid of the container to rise 2m with 3N of force. What is the total change in energy of the system?
Options
10J
4J
– 10J
– 4J
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Solution
4J
Explanation:
Write the equation from the first law of thermodynamics.
ΔU = Q – W
Write the expression of work done.
W = F × Δx
W = (3N) × (2m)
W = 6J
Substitute 10J for Q and 6J for W to find a change in energy.
ΔU = 10J – 6J
ΔU = 4J
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