It takes 15 s to raise a 1200-kg car and the supporting 300-kg hydraulic car-lift platform to a height of 2.8 m. the velocity of the lift increases uniformly from zero to its maximum value at mid-height in 7.5 s and then decreases uniformly to zero in 7.5 s. knowing that the peak power output of the hydraulic pump is 9 kw when the velocity is maximum, determine the maximum lift force provided by the pump.