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QJEEM24Ph8ac9: JEE Main 2024 Physics - Class 11 JEEM24Ph8ac9 Solution: The potential energy function (in ) of a particle in a region…

The potential energy function (in JJ ) of a particle in a region of space is given as U=(2x2+3y3+2z)U=\left(2 x^2+3 y^3+2 z\right) . Here x,yx, y and zz are in meter. The magnitude of xx -component of force (in NN ) acting on the particle at point P(1,2,3)mP(1,2,3) \mathrm{m} is :

Multiple Choice Options

  • A 4
  • B 2
  • C 8
  • D 6

Step-by-Step Verified Solution

The force acting on a particle can be determined from the potential energy function by using the negative gradient. In three-dimensional space, the force vector F is related to the potential energy function UU by:

F=−∇U\mathbf{F} = -\nabla U

where ∇U\nabla U (the gradient of UU ) is a vector with components given by the partial derivatives of UU with respect to xx , yy , and zz :

∇U=(∂U∂x,∂U∂y,∂U∂z)\nabla U = \left( \frac{\partial U}{\partial x}, \frac{\partial U}{\partial y}, \frac{\partial U}{\partial z} \right)

Given the potential energy function:

U=2x2+3y3+2zU = 2x^2 + 3y^3 + 2z

Calculate the partial derivative of UU with respect to xx to find the xx -component of the force:

Partial Derivative with respect to xx :

∂U∂x=∂∂x(2x2+3y3+2z)=4x\frac{\partial U}{\partial x} = \frac{\partial}{\partial x}(2x^2 + 3y^3 + 2z) = 4x

    Calculate the xx -component of the force:

    Since Fx=−∂U∂xF_x = -\frac{\partial U}{\partial x} , the xx -component of the force is:

    Fx=−4xF_x = -4x

      Evaluate at point P(1,2,3)P(1,2,3) :

      Substitute x=1x = 1 into the expression for FxF_x :

      Fx=−4(1)=−4F_x = -4(1) = -4

      The magnitude of the xx -component of the force is:

      ∣Fx∣=4 N|F_x| = 4 \, \text{N}

      Thus, the correct answer is Option A: 4.

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