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JAMB Physics 2006 Question 15

Question 15

Simple Machines

I. Work done by load is always less than the work done by effort
II. All machines are made of levers, pulleys, screws and gear wheels.
III. A fishing rod is a machine
IV. Effort is always larger than load.
Which of the statements above about machines are true?

  1. A.III and IV
  2. B.I and II
  3. C.I and III
  4. D.II and III
Show the answer and explanation

Answer: C (I and III)

Explanation

Friction makes useful work output less than work input (I true), and a fishing rod is a lever, so it is a machine (III true). Not all machines are levers, pulleys, screws or gears, and many machines lift a load bigger than the effort.