Consider the following statements with regard to Pascal’s Law:
- Pascal’s Law states that a change in pressure applied to an enclosed incompressible fluid is transmitted undiminished to all portions of the fluid and to the walls of its container.
- Hydraulic lifts and braking systems in automobiles are based on the principle that pressure decreases with increased area of application.
- Pascal’s Law is not valid for compressible fluids like gases because the pressure is not transmitted uniformly due to density variations.
Which of the above statements is/are correct?
A. 1 and 2 only
B. 1 and 3 only
C. 2 and 3 only
D. 1, 2 and 3
Answer: B. 1 and 3 only
Explanation:
- Statement 1 is correct:
This is the fundamental statement of Pascal’s Law. In a closed system with incompressible fluid (like oil or water), any external pressure is transmitted equally in all directions. - Statement 2 is incorrect:
Hydraulic systems like lifts work on force amplification, not pressure reduction. In fact, pressure remains constant, but force increases due to increased area (Force = Pressure × Area). The pressure is the same on both pistons, but a larger piston results in a larger output force, not a lower pressure. - Statement 3 is correct:
Pascal’s Law assumes the fluid is incompressible. In gases (compressible fluids), the pressure transmission is not always uniform because gases can compress, leading to non-uniform density and non-instantaneous pressure transmission.
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