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JEE MainPhysicsWork, Power and Energy

A particle of mass 2 kg moves along a straight line starting from rest. The power delivered to it by the net force is given by P = 4t^3 W, where t is the time in seconds. The magnitude of the net force acting on the particle as a function of time is :

Options

  1. A4t N
  2. B4 2 t N
  3. C12t^2 N
  4. D4t^2 N

Correct answer

A. 4t N

Step-by-step solution

Power P = F v = m a v = m v dv dt Given m = 2 kg and P = 4t^3 W, we have: 2 v dv dt = 4t^3 v dv = 2t^3 dt Integrating both sides from t = 0 (where v = 0 ) to t : ₀^v v' dv' = ₀^t 2t'^3 dt' v^2 2 = 2t^4 4 v^2 = t^4 v = t^2 The acceleration of the particle is: a = dv dt = 2t The magnitude of the net force is: F = ma = 2(2t) = 4t N Answer: 4t N

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