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MHT CET · Physics · Work Power Energy

A particle is displaced from point \(\mathrm{P}(3 \mathrm{~m}, 4 \mathrm{~m}, 5 \mathrm{~m})\) to a point \(Q(2 m, 3 m, 4 m)\) under a constant force \(\vec{F}=(3 \hat{i}+4 \hat{j}+5 \hat{k}) N\). The work done by the force in this process is

  1. A \(+10 \mathrm{~J}\)
  2. B \(+4 \mathrm{~J}\)
  3. C \(-8 \mathrm{~J}\)
  4. D \(-12 \mathrm{~J}\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(-12 \mathrm{~J}\)

Step-by-step Solution

Detailed explanation

\( \vec{r} = (2-3)\hat{i} + (3-4)\hat{j} + (4-5)\hat{k} = -\hat{i} - \hat{j} - \hat{k} \) \( W = \vec{F} \cdot \vec{r} = (3\hat{i} + 4\hat{j} + 5\hat{k}) \cdot (-\hat{i} - \hat{j} - \hat{k}) \)