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JEE Main 2019 (8 Apr, Shift 1) · Work by a Variable Force

Work by a Variable Force question from JEE Main 2019 (8 Apr, Shift 1)

Q18JEE Main 2019 · 8 APR · SHIFT 1Medium

Work by a Variable Force

A particle moves in one dimension from rest under the influence of a force that varies with the distance travelled by the particle as shown in the figure. The kinetic energy of the particle after it has travelled 3m is:

Figure

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Answer: (a)

  1. Starting from rest, K=W=K = W = area under the FF-xx graph.
  2. 0→20 \to 2 m: rectangle =2×2=4 J= 2 \times 2 = 4\text{ J}
  3. 2→32 \to 3 m: trapezium =12(2+3)(1)=2.5 J= \frac{1}{2}(2 + 3)(1) = 2.5\text{ J}
  4. K=4+2.5=6.5 JK = 4 + 2.5 = 6.5\text{ J}, so the answer is (a).
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