Intravenous infusions are often made under gravity.
at what height should the bottle be placed so the liquid pressure is 700 mm-h2o?

The pressure exerted by a column of liquid of height h and density ρ is given by the hydrostatic pressure equation p = ρgh, where g is the gravitational acceleration.
p = ρghρ = 1000 kg/m3g = 9.81 m/s2convert mm h20 to Pa700 mm H20 ( 9.81 pa / 1 mm h2o)= 6867 Pa 
6867 Pa = (1000 kg/m3)(9.81 m/s2)hh = 0.7 mh = 700 mm

490 n  f=125n a=2.5m/s2