Question:
Steam engine efficiency 30% wastes heat 2.1×10$^9$ J/min. Work done is:
Steam engine efficiency 30% wastes heat 2.1×10$^9$ J/min. Work done is:
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Efficiency problems always follow: \(Q_{in} = W + Q_{out}\).
Updated On: Jul 18, 2026
- 7×10$^8$
- 8×10$^8$
- 9×10$^8$
- 1×10$^9$
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The Correct Option is C
Solution and Explanation
Step 1: Efficiency relation.
\[ \eta = \frac{W}{Q_{in}} \]
Step 2: Heat relation.
\[ Q_{in} = W + Q_{out} \]
Step 3: Substitute.
\[ 0.3 = \frac{W}{W + 2.1\times10^9} \]
Step 4: Solve.
\[ 0.7W = 2.1\times10^9 \]
Step 5: Result.
\[ W = 9\times10^8 \]
Step 6: Final answer.
\[ \boxed{9\times10^8} \]
\[ \eta = \frac{W}{Q_{in}} \]
Step 2: Heat relation.
\[ Q_{in} = W + Q_{out} \]
Step 3: Substitute.
\[ 0.3 = \frac{W}{W + 2.1\times10^9} \]
Step 4: Solve.
\[ 0.7W = 2.1\times10^9 \]
Step 5: Result.
\[ W = 9\times10^8 \]
Step 6: Final answer.
\[ \boxed{9\times10^8} \]
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