Pressure, Fluids, & Pascal’s Law

 Blaise Pascal was a French mathematician and physicist who studied, among other things, the behaviour of fluids.  Pascal found that when fluids in a container are put under pressure, they push in all directions. That is why balloons bulge when filled or squeezed.  Pascal’s Law – A force applied to a fluid is distributed equally through all parts of the fluid.  Egg Demo Egg Demo  Like what we’ve seen using pneumatic and hydraulic systems, this ability of fluids to transfer force is used in nature and in many devices.

 Think about the previous lab. Connecting 2 syringes of different sizes together and pushing on their plungers, you should notice two things: 1. The plunger in the smaller syringe moves farther than the plunger in the larger syringe. 2. The plunger in the smaller syringe is easier to move than the plunger in the larger syringe.

 This figure shows that when fluid in a small chamber is pushed into a larger chamber, the fluid is spread throughout a bigger volume. The distance moved by the smaller plunger is more than the larger plunger. However, the force applied to the small piston is transferred to every part of the fluid equally. Since the large piston has an area 5 times larger, the force from the small piston is multiplied five times. Hydraulic System (1:45-3:30)

 We use Pascal’s Law in devices such as hydraulic brakes, hydraulic lifts, and heavy equipment, where we need to multiply the force.  Pascal's Law & Hydraulic Brake System Pascal's Law & Hydraulic Brake System  Remember, liquids cannot be compressed very much. When you apply force to one part of a hydraulic system, the force transfers immediately to all other parts.  Since gases are much more compressible than liquids, pneumatic systems are often used when a “cushioning” effect is needed (e.g., bus doors).

1. Describe Pascal’s Law in your own words. Use a diagram to support your answer. 2. Why do deep-sea divers require greater protection than scuba-divers?