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JAMB Physics 2015 (CBT) Question 4

Question 4

Newton's Laws and Momentum

What force has to be exerted on a mass 60kg to give it an acceleration of 10ms−2 vertically upwards? [g=10ms−2]

  1. A.600N
  2. B.1200N
  3. C.400N
  4. D.300N.
Show the answer and explanation

Answer: B (1200N)

Explanation

The force must hold up the weight and also accelerate the mass: F − mg = ma, so F = m(g + a) = 60 × 20 = 1200 N.