MOST MACHINES THAT MOVE VERY LARGE OBJECTS USE A HYDRAULIC SYSTEM. HYDRAULIC SYSTEM: System that uses a liquid under pressure to move loads. Before hydraulic systems most construction was done by hand Ex) Pyramids, castles, great wall of china PNEUMATIC SYSTEM: System that uses gas under pressure to move loads.
PRESSURE IN FLUIDS
PRESSURE: Measure of the amount of force applied to a given area.
Pressure (Pa) = Force (N)/Area (m²)
Pressure is measured in Pascals (Pa)
PASCAL’S LAW: Pressure applied to an enclosed fluid is transmitted equally in all directions through out the fluid.
fluids do not become compressed, unlike gases.
pushing force (pressure) is transmitted equally in all directions within the fluid (I wrote it twice, because it’s super important)
HOW TO CREATE PRESSURE
A PISTON CREATES PRESSURE Hydraulic systems work because of pistons.
PISTON: A disk that fits tightly inside a cylinder.
As the disk moves it either draws fluid/gas in or pushes fluid/gas out
Commonly used in engines and hydraulic systems
Size can vary widely
HYDRAULIC SYSTEM:
HYDRAULIC SYSTEM: A hydraulic system uses a liquid under pressure to move loads. It is a combination of a smaller piston in a pipe, attached by a flexible tube to a larger piston in a larger pipe.
Pushing the smaller piston requires small amounts of force but it must be pushed a greater distance
As a result the larger piston pushes with a large amount of force but it moves a much smaller distance
INPUT PISTON: Used to apply force to the fluid (usually smaller) OUTPUT PISTON: Transfers the force to the load (usually larger)
CALCULATING MECHANICAL ADVANTAGE USING PRESSURE
From Pascal’s law, we know that the pressure the small piston creates is the same everywhere in the fluid. So the large piston has a larger area and is able to multiply the pressure because of its larger area. The force and area at each piston act as ratios that have to be equal.
Small Piston Pressure = Large Piston Pressure
SO... WE CAN SAY THAT: Force of the Small Piston / Area of the small piston = Force of the Large Piston / Area of the large piston
RE-WRITTEN WE EXPRESS IT AS SUCH: F (small)/A (small) = F (large)/A (large)
PRESSURE EXERTED EQUALLY IN THE FLUID PROVIDES THE MECHANICAL ADVANTAGE. Mechanical Advantage (MA) = Output Force/Input Force