A particle of mass m is initially at rest at the origin. It is subjected to a force and starts moving along…

A particle of mass m is initially at rest at the origin. It is subjected to a force and starts moving along the x - axis. Its kinetic energy changes with time as dK/dt=γt, where γ is a positive constant of appropriate dimensions. Which of the following statements is (are) true?
  1. The force applied on the particle is constant
  2. The speed of the particle is proportional to time
  3. The distance of the particle from the origin increases linearly with time
  4. Since force is constant, it is conservative.

Solution

Given the change in kinetic energydkdt=γt.

Kinetic energy is expressed as k=12mv2.
   dkdt=mvdvdt=γt
Integrating the above relation, 

m0vvdv=γ0ttdt
mv22=γt22
v=γmt; υt ... (i)
a=dvdt=γm=constant
Since F=ma
  F=mγm=γm=constant

Asked in: JEE Advanced 2018 (Paper 2)

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