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JAMB Physics 1995 Question 7

Question 7

Newton's Laws and Momentum

The acceleration of the system shown above is

Diagram for this question
  1. A.2 m s−2
  2. B.4 m s−2
  3. C.6 m s−2
  4. D.8 m s−2
Show the answer and explanation

Answer: B (4 m s−2)

Explanation

Taking the plane as smooth and g = 10 m s−2: the hanging 30 kg pulls with 300 N, and the 20 kg block on the 30° slope pulls back with 20 × 10 × sin 30° = 100 N. a = (300 − 100)/(30 + 20) = 4 m s−2.