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Zorluk: OrtaPascal's Principle and Hydraulics

A hydraulic theater stage lift is used to raise a heavy set piece. The output piston supporting the stage has a cross-sectional area of 120 in2120 \text{ in}^2, while the input piston connected to the control system has an area of 8 in28 \text{ in}^2. If the set piece and stage exert a combined downward force of 2,400 lbs2,400 \text{ lbs} on the output piston, how much input force, in pounds, must be applied to the input piston to hold the stage steady?

Cevap: 160 lbs

Cevap

160
Based on Pascal's Principle, an enclosed fluid transmits pressure equally. The stage creates a pressure of 20 psi20 \text{ psi} (2,400 lbs/120 in22,400 \text{ lbs} / 120 \text{ in}^2). Because this 20 psi20 \text{ psi} is transmitted to the input piston, which has an area of 8 in28 \text{ in}^2, the required force is 20 psi×8 in2=160 lbs20 \text{ psi} \times 8 \text{ in}^2 = 160 \text{ lbs}.

Adım Adım Çözüm

1
State Pascal's Principle for the system.
Pin=PoutP_{in} = P_{out}, meaning FinAin=FoutAout\frac{F_{in}}{A_{in}} = \frac{F_{out}}{A_{out}}
Pascal's Principle dictates that pressure applied to an enclosed fluid is transmitted equally in all directions.
2
Calculate the pressure at the output piston.
P=2,400 lbs120 in2=20 psiP = \frac{2,400 \text{ lbs}}{120 \text{ in}^2} = 20 \text{ psi}
This establishes the uniform pressure throughout the entire hydraulic system.
3
Calculate the required input force.
Fin=P×Ain=20 psi×8 in2=160 lbsF_{in} = P \times A_{in} = 20 \text{ psi} \times 8 \text{ in}^2 = 160 \text{ lbs}
Applying the system pressure to the smaller area of the input piston yields the necessary input force.

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