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Question
Two cylindrical vessels fitted with pistons A and B of area of cross-section 8 cm2 and 320 cm2 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:
- the pressure on piston A,
- the pressure on piston B, and
- the thrust on piston B.
Solution
Given that the force applied to the smaller piston A is 4 kg
Area of cross-section of piston A = 8 cm²
Area of cross-section of piston B = 320 cm²
(i) Pressure acting on piston A in the downward direction = `"Thrust"/"Area"`
= `(4 "kg")/(8 "cm"^2)`
∴ Pressure acting on piston A = 0.5 kg cm-2
(ii) According to Pascal's Law
Pressure acting on piston B = Pressure acting on Piston A = 0.5 kg cm-2
(iii) Thrust acting on piston B in the upward direction
= Pressure × Area of B
= 4 kg × `(320 "cm"^2)/(8 "cm"^2)`
∴ Thrust acting on piston B in the upward direction = 160 kgf.
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