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A particle of mass  m is moving in a circular path of constant radius r such that its centripetal acceleration `a_c` is varying with time t as `a_c = k^2 r t^2`. The power is


Options:
A .  `2 pi mk^2r^2 t`
B .  `mk^2 r^2t`
C .  `(mk^4 r^2 t^5)/(3)`
D .  zero
Answer: Option B

`a_c = v^2/r =  k^2 r t^2`

`because         v = krt`

The tangential accelerationis

   `a_1 = (dv)/(dt) = (d(rt))/(dt) = kr`

The work done by centripetal force will be zero.

so , power is delivered to the particle by only tangential force which acts in he same direction of instantaneous   velocity .

`:.`        power = `F_1 v`

                      = `ma_1 krt`

                     = `m(kr) (krt) =  mk^2 r^2 t`



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