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JAMB Physics 2001 Question 8

Question 8

Simple Machines

The efficiency of a machine is always less than 100% because the

  1. A.work output is always greater than the work input
  2. B.load lifted is always greater than the effort applied
  3. C.effort applied is always greater than the load lifted
  4. D.velocity ratio is always greater than the mechanical advantage.
Show the answer and explanation

Answer: D (velocity ratio is always greater than the mechanical advantage.)

Explanation

Efficiency = MA/VR. Friction and moving parts waste some work, so MA is always less than VR and the efficiency is below 100%.