Find the expression for the force exerted on the particle as a function of time

A particle mass is at rest at t=0. Its momentum for t>0 is given by px=6t^2 kg m/s, where t is in s. Find an expression for Fx (t), the force exerted on the particle as a function of time.

Thanks :)

(1) momentum = m * v = p

(2) F = m * a

(3) a(t) = dv / dt

Therefore,
(4) F(t) = m * dv / dt = d(m * v) / dt = dp / dt

= d(6t^2) / dt

= 12t kg m / s^2

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