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JAMB Physics 1981 Question 28

Question 28

Friction

A mass of 2 kg on a surface (μ = ½) is connected to second mass of 4 kg over a frictionless pulley as shown in Fig. 4. If the acceleration due to gravity is 9.8 m s−2 then the masses will

Diagram for this question
  1. A.accelerate at 4.9 m s−2
  2. B.remain stationary
  3. C.accelerate at 9.8 m s−2
  4. D.accelerate at 19.6 m s−2
  5. E.Accelerate at 39.2 m s−2.
Show the answer and explanation

Answer: A (accelerate at 4.9 m s−2)

Explanation

Pulling force = 4 × 9.8 = 39.2 N; friction = ½ × 2 × 9.8 = 9.8 N. Net force 29.4 N on a total mass of 6 kg gives a = 4.9 m s−2.