Question:

When a spring is stretched by a distance $x$, it exerts a force, given by $F = (-5x - 16x^{3})\, N$. The work done, when the spring is stretched from $0.1 \,m$ to $0.2\, m $ is

Updated On: Sep 2, 2023
  • $8.7 \times 10^{-2}\,J$
  • $12.2 \times 10^{-2}\, J$
  • $8.7 \times 10^{-1}\,J$
  • $12.2 \times 10^{-1}\,J$
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The Correct Option is A

Solution and Explanation

$F=-5x-16x^{3}=-(5+16x^{2})x=-kx$ $\therefore k=5+16x^{2}$ Work done, $W=\frac{1}{2}k_{2}x^{2}_{2}-\frac{1}{2}k_{1}x^{2}_{1}$ $=\frac{1}{2}[5+16(0.2)^{2}](0.2)^{2}=\frac{1}{2}[5+16(0.1)^{2}] (0.1)^{2}$ $=2.82 \times 4 \times 10^{-2}-2.58\times 10^{-2}$ $=8.7 \times 10^{-2}\,J$
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Concepts Used:

Work

Work is the product of the component of the force in the direction of the displacement and the magnitude of this displacement.

Work Formula:

W = Force × Distance

Where,

Work (W) is equal to the force (f) time the distance.

Work Equations:

W = F d Cos θ

Where,

 W = Amount of work, F = Vector of force, D = Magnitude of displacement, and θ = Angle between the vector of force and vector of displacement.

Unit of Work:

The SI unit for the work is the joule (J), and it is defined as the work done by a force of 1 Newton in moving an object for a distance of one unit meter in the direction of the force.

Work formula is used to measure the amount of work done, force, or displacement in any maths or real-life problem. It is written as in Newton meter or Nm.