Measuring Pressure: More Practice

Pascal’s Principle: Student Success Criteria I can state Pascal's principle, explain its applications in the transmission of forces in fluid systems, and conduct an laboratory investigation to demonstrate it.

SPH4C

Compressibility Recall that liquids are not very compressible: their volume remains more or less constant even if pressure is applied.

Pascal’s Principle Therefore, pressure applied to an enclosed liquid is transmitted to every part of the liquid and to the walls of the container. A hydraulic braking system transfers pressure from the brake lever through the system.

The hydraulic press Pascal used this principle in the design of a device called the hydraulic press: a device in which a small force on a small piston is transmitted through an enclosed liquid and applies a large force on a large piston.

The hydraulic press I.e., the pressure (p S ) on the small piston equals the pressure (p L ) on the large piston: If A is increased, then F is also increased.

The hydraulic press: Example A force of 14 N is applied to a piston of area 0.01 m 2, which is connected to another piston of area 0.25 m 2. What is the force on the larger piston?

The hydraulic press: Example A force of 14 N is applied to a piston of area 0.01 m 2, which is connected to another piston of area 0.25 m 2. What is the force on the larger piston?

The hydraulic press: Example A force of 14 N is applied to a piston of area 0.01 m 2, which is connected to another piston of area 0.25 m 2. What is the force on the larger piston?

The hydraulic press: Example A force of 14 N is applied to a piston of area 0.01 m 2, which is connected to another piston of area 0.25 m 2. What is the force on the larger piston?

Mechanical advantage The Ideal Mechanical Advantage (IMA) of the system would be: & Actual Mechanical Advantage (AMA) of the system would be.

Mechanical advantage The Ideal Mechanical Advantage (IMA) of the system would be: & Actual Mechanical Advantage (AMA) of the system would be.

Mechanical advantage The Ideal Mechanical Advantage (IMA) of the system would be: & Actual Mechanical Advantage (AMA) of the system would be.

Distance However, since the volume of the larger cylinder is obviously larger, the distance the larger cylinder is displaced is smaller.

Brakes Car brakes incorporate both levers and hydraulics: the distance from the pedal to the pivot is four times the distance from the cylinder to the pivot, so the force at the pedal will be increased by a factor of four before it is transmitted to the cylinder. (2 nd class lever).

Brakes The diameter of the brake cylinder is three times the diameter of the pedal cylinder, increasing the area and therefore the force by a factor of nine. All together, this system increases the force of your foot by a factor of 36 (4 x 9 = 36).

Brakes So if you put 100 N of force on the pedal, 3600 N will be generated at the wheel squeezing the brake pads

More Practice Pascal’s Principle Lab Activity