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JEE Main202127 Jul 2021Evening ShiftPhysicsWork, Power and EnergyActual

An automobile of mass m accelerates starting from the origin and initially at rest, while the engine supplies constant power P . The position is given as a function of time by:

Options

  1. A9 P 8   m 1 2 t 3 2
  2. B8 P 9   m 1 2 t 2 3
  3. C9 m 8 P 1 2 t 3 2
  4. D8 P 9   m 1 2 t 3 2

Correct answer

D. 8 P 9   m 1 2 t 3 2

Step-by-step solution

P = const P = F V = m v 2   d v d x ∫ 0 x P m dx = ∫ 0 v v 2   dv P x m = v 3 3 3 P x m 1 3 = v = d x d t 3 P m 1 3 ∫ 0 t d t = ∫ 0 x x - 1 3 d x ⇒ x = 8 P 9   m 1 2 t 3 2

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