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JAMB Physics 1983 Question 32

Question 32

Elasticity

The total length of a spring when a mass of 20 g is hung from its end is 14 cm, while its total length is 16 cm when a mass of 30 g is hung from the same end. Calculate the unstretched length of the spring assuming Hooke's law is obeyed.

  1. A.9.33 cm
  2. B.10.00 cm
  3. C.10.66 cm
  4. D.12.00 cm
  5. E.15.00 cm
Show the answer and explanation

Answer: B (10.00 cm)

Explanation

The extra 10 g stretches it 2 cm, so 20 g stretches it 4 cm. Unstretched length = 14 − 4 = 10 cm.