Two cylindrical vessels fitted with pistons A and B of area of cross section 8 cm 2 and 320 cm 2 respectively, are joined at their bottom by a tube and they are completely filled with water. When a mass of 4 kg is placed on piston A, find : (i) the pressure on piston A, (ii) the pressure on piston B, and (iii) the thrust on piston B.

(i) Force on the narrow piston A = 4 kg

A_A = 8 cm ²

A_B = 320 cm ²

Pressure (P_A) = 4/8 = 0.5 kg cm^-2

Hence, P_A = 0.5 kg cm^-2

(ii) As we know, by the principle of hydraulic machine

Pressure on piston A = pressure on piston B

Hence, P_B = 0.5 kg cm^-2

(iii) Thrust on piston B is acting in the upward direction, which is given by

Thrust = 0.5 × 320 = 160 kgf

Hence, thrust on piston B = 160 kgf