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JEE Main20253 Apr 2025Evening ShiftPhysicsWork, Power and EnergyActual

A block of mass 1 kg , moving along x with speed v _ i =10 ~m / s enters a rough region ranging from x =0.1 ~m to x =1.9 ~m . The retarding force acting on the block in this range is F _ r =- kx N , with k =10 ~N / m . Then the final speed of the block as it crosses rough region is

Options

  1. A10 ~m / s
  2. B4 ~m / s
  3. C6 ~m / s
  4. D8 ~m / s

Correct answer

D. 8 ~m / s

Step-by-step solution

aligned & a= F m =-10 x & v d v d x =-10 x aligned ₁₀^ v vdv =-10 _ 0.1 ^ 1.9 xdx aligned & v^2-100 2 =-10 ( 1.9^2-0.1 2 )^2 & v=8 ~m / s aligned

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