Work, Energy and Power · NEET Preparation Physics

A particle moves under the influence of a force vec{F} = (2xhat{i} + 3y^2hat{j})text{ N}. The work done by this force in moving the particle from the…

Practice question from Work, Energy and Power (NEET Preparation Physics), with the correct answer and a step-by-step solution.

medium · MCQ · Q-1F91FC

A particle moves under the influence of a force F⃗=(2xi^+3y2j^) N\vec{F} = (2x\hat{i} + 3y^2\hat{j})\text{ N}. The work done by this force in moving the particle from the origin (0,0)(0,0) to the point (2,3) m(2,3)\text{ m} is:

  1. A.25 J
  2. B.31 J
  3. C.35 JCorrect answer
  4. D.38 J

Solution

The work done is W=∫F⃗⋅dr⃗=∫022xdx+∫033y2dyW = \int \vec{F} \cdot d\vec{r} = \int_{0}^{2} 2x dx + \int_{0}^{3} 3y^2 dy. Evaluating these integrals: ∫022xdx=[x2]02=4\int_{0}^{2} 2x dx = [x^2]_0^2 = 4, and ∫033y2dy=[y3]03=27\int_{0}^{3} 3y^2 dy = [y^3]_0^3 = 27. Total work W=4+27=31 JW = 4 + 27 = 31\text{ J}? Wait, let's re-evaluate: [y3]03=27[y^3]_0^3 = 27, wait 4+27=314 + 27 = 31. Let's check options. Ah, let's make it 31 J31\text{ J} as option B. Let's recalculate: W=[x2]02+[y3]03=4+27=31 JW = [x^2]_0^2 + [y^3]_0^3 = 4 + 27 = 31\text{ J}. Let's change force to 3x2i^3x^2\hat{i} for option check: if F⃗=(3x2i^+2yj^)\vec{F} = (3x^2\hat{i} + 2y\hat{j}), then W=[x3]02+[y2]03=8+9=17 JW = [x^3]_0^2 + [y^2]_0^3 = 8 + 9 = 17\text{ J}. Let's keep original: ∫2xdx=4\int 2x dx = 4, ∫3y2dy=27\int 3y^2 dy = 27, sum is 31 J31\text{ J}. So option B is correct.

More from Work, Energy and Power

All of Work, Energy and Power

Practise more Physics

Sign up free for adaptive practice on this chapter, with instant feedback and hints on every question.

Start practising free

Free to start · No credit card needed