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NEET 2026
Exam
NEET
Year
2026
Subject
Physics
Chapter
Chapter

NEET 2026 · Physics · Chapter

A block of mass 2 kg is projected with an initial speed of 14 m/s...

A block of mass 2 kg2 \text{ kg} is projected with an initial speed of 14 m/s14 \text{ m/s} on a rough horizontal surface. The coefficient of kinetic friction between the block and the surface is 0.20.2. After traveling a distance of 24 m24 \text{ m}, the block collides head-on with a massive stationary bumper. It rebounds and travels a distance of 9 m9 \text{ m} before coming to rest. What is the magnitude of the impulse imparted by the bumper to the block? (Take g=10 m/s2g = 10 \text{ m/s}^2)

Options

  1. A8 N s8 \text{ N s}
  2. B16 N s16 \text{ N s}
  3. C28 N s28 \text{ N s}
  4. D32 N s32 \text{ N s}

Correct answer

D. 32 N s32 \text{ N s}

Step-by-step solution

The deceleration of the block due to kinetic friction is given by:

a=−μkg=−0.2×10=−2 m/s2a = -\mu_k g = -0.2 \times 10 = -2 \text{ m/s}^2

Let v1v_1 be the velocity of the block just before it collides with the bumper. Using the third equation of motion:

v12=u2+2ad1v_1^2 = u^2 + 2a d_1

v12=(14)2+2(−2)(24)v_1^2 = (14)^2 + 2(-2)(24)

v12=196−96=100⇒v1=10 m/sv_1^2 = 196 - 96 = 100 \Rightarrow v_1 = 10 \text{ m/s}

Let v2v_2 be the velocity of the block just after rebounding. Since it comes to rest after traveling d2=9 md_2 = 9 \text{ m}:

0=v22+2ad20 = v_2^2 + 2a d_2

v22=2(2)(9)=36⇒v2=6 m/sv_2^2 = 2(2)(9) = 36 \Rightarrow v_2 = 6 \text{ m/s}

The impulse JJ imparted by the bumper is equal to the change in momentum of the block. Taking the initial direction of motion as positive:

J=m(vf−vi)=m(−v2−v1)J = m(v_f - v_i) = m(-v_2 - v_1)

J=2(−6−10)=−32 N sJ = 2(-6 - 10) = -32 \text{ N s}

The magnitude of the impulse is 32 N s32 \text{ N s}.

Answer: 32 N s32 \text{ N s}
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