8.1.7 Pascal's Principle and Examples of Hydrostatics

Question 1

Pascal’s Principle and Examples of Hydrostatics

Answer 1

• Hydrostatics is the physics of fluids at rest and in equilibrium.
• Pascal’s principle: Pressure applied to an enclosed fluid is transmitted throughout the fluid and to the walls of the containing vessel.
• Hydrostatic lifts and hydraulic brakes are two examples of applications of Pascal’s principle.•A barometer is a device used to measure atmospheric pressure

Question 2

When there is no car on the platform and no external force on the small piston, a hydraulic car lift is balanced. The area of the large piston, which supports a car, is 100 cm2 and the area of the small piston 12 cm2. How much force must be applied to the small piston to lift a 10,000 N car at a constant speed?

Answer 2

1,200 N

Question 3

A constant force is applied to the smaller piston of a hydraulic jack. If the cross-sectional area of the large piston is increased, the pressure it exerts ____________.

Answer 3

is unchanged

Question 4

Which of the following is not correct?

Answer 4

When a pressure is applied to a liquid in hydrostatic equilibrium, the pressure on the surface of the liquid is greater than at other points in the liquid.

Question 5

Which of the following is not correct?

Answer 5

If a force is applied to a fluid enclosed in a vessel, the pressure decreases as 1 / x, where x is the distance from the source of the force.

Question 6

Consider a piston with small cross-sectional area A1 exerting a force F1 on the surface of a liquid, and a larger piston with cross-sectional area A2 exerting a force F2 on the surface of a liquid at its position. Which of the following is incorrect?

Answer 6

F2 = F1(A1/A2)

Question 7

A constant force is applied to the smaller side of a hydraulic jack. If the cross-sectional area of the larger piston of a hydraulic jack is increased, the load it can lift _______________.

Answer 7

increases

Question 8

A hydraulic car lift is balanced when there is no car on the platform and no external force on the small piston. Consider an automobile with a mass of 1,800 kg and suppose that the pistons have radii of r1 = 2.0 cm and r2 = 10 cm. What is the value of F1 needed to start the rise of the automobile?

Answer 8

705.6 N

Question 9

Consider a fluid of constant density in hydrostatic equilibrium. Which of the following is not correct?

Answer 9

Because the density p in Pascal’s principle is constant, Pascal’s principle only applies to liquids and not gases