A vertical cylinder contains water and is closed at the bottom by a horizontal circular piston of area 0.030m2. The upper water surface is open to the atmosphere. If the piston is 5.0 m below the water surface, what magnitude of upward force must be applied to the piston (in addition to its weight) to keep it in equilibrium? Take ρwater=1.0×103kgm−3 and g=9.8ms−2.
(a) 4.9×103N
(b) 1.5×102N
(c) 1.5×103N
(d) 4.9×104N