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Concepts Of Physics MCQ Edition [Volume 1]PhysicsNewton's Laws of Motion

As depicted in the figure, a uniform rod of length 30 cm and mass 3.0 kg is pulled by strings subjected to constant forces of 20 N and 32 N . Determine the force exerted by the 20 cm part of the rod on the 10 cm part. All surfaces are smooth, and the strings and pulleys are light.

Options

  1. A16 N
  2. B24 N
  3. C12 N
  4. D28 N

Correct answer

B. 24 N

Step-by-step solution

Total mass of the rod, M = 3.0 kg Total length of the rod, L = 30 cm The net force acting on the rod is: F_ net = 32 - 20 = 12 N towards the right. The acceleration of the rod is: a = F_ net M = 12 3.0 = 4 m/s ^2 Since the rod is uniform, the mass of the 10 cm part is: m₁ = 10 30 3.0 = 1.0 kg Let F be the force exerted by the 20 cm part on the 10 cm part. The forces acting on the 10 cm part in the horizontal direction are 20 N to the left and F to the right. Applying Newton's second law to the 10 cm part: F - 20 =

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