Chapter 7 Work, Energy, and Simple Machines - Part 1

Why is the efficiency of real-world machines always less than 100%?

Type: MCQ • Marks: 1
Why is the efficiency of real-world machines always less than 100%?
Options
A. Because work done is zero
B. Because machines have no mass
C. Because energy is created
D. Due to friction and energy loss as heat
Explanation
Friction and air resistance dissipate mechanical energy into heat, lowering efficiency.
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Class 9th Science (MCQ)

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