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JEE Main 202325 JanuaryMorning Shift
Exam
JEE Main
Year
2023
Date
25 January
Shift
Morning Shift
Subject
Physics
Chapter
Work, Power and Energy

JEE Main 2023 · 25 January · Morning Shift · Physics · Work, Power and Energy

An object of mass m initially at rest on a smooth horizontal plane...

An object of mass mm initially at rest on a smooth horizontal plane starts moving under the action of force F=2NF = 2N. In the process of its linear motion, the angle θ\theta (as shown in figure) between the direction of force and horizontal varies as θ=kx\theta = kx, where kk is a constant and xx is the distance covered by the object from its initial position. The expression of kinetic energy of the object will be E=nksinθE = \dfrac{n}{k}sin\theta. The value of nn is ______.

An object of mass m initially at rest on a smooth horizontal plane starts moving under the action of force F = 2N . In

Correct answer

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Step-by-step solution

An object of mass m initially at rest on a smooth horizontal plane starts moving under the action of force F = 2N . In

As seen in the free body diagram of the object, normal force NN, weight mgmg and force in parallel and perpendicular directions are acting.

Using Newton's law of motion

Along horizontal direction, Fcosθ=maFcos\theta = ma

⇒2cos⁡(kx)=mvdvdx⇒ 2\cos ( kx ) = mv\dfrac{d v}{d x}

Integrating the above relation, we have

∫0vvdv=2∫0xcos⁡(kx)dx{∫}_{0}^{v}v d v = 2{∫}_{0}^{x}\cos ( kx ) d x

⇒mv22=2ksinkx⇒ \dfrac{m{v}^{2}}{2} = \dfrac{2}{k}sinkx

Thus, kinetic energy of the object will be K.E.=2ksinθK . E . = \dfrac{2}{k}sin\theta

Thus, the value of n=2n = 2.

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