A body of mass m,  accelerates uniformly from rest to V1  in time  t1.  The instantaneous power delivered to the Body as a function of time ‘t’ is

Acceleration   a   =   v1t1---(1)∴   velocity   v  =  u+at = 0 + a t-----(2) substitute                       v=at equation (1) in (2)                             v  =  v1t1 ⋅ t ---------(3)∴   power   p  =   F×V                             p  =   m⋅a⋅v   --------(4)substitute equations (3),(1) in (4)                                  p  =   m⋅ v1t1⋅ v1t1⋅t∴       p  =    mv12tt12