The pressure applied on one part of container with fluid is transmitted equally in all directions. V’ Pressure on one side is equal to the pressure on the other side of hydraulic press and lift Pascal Law: “The pressure exerted anywhere in a mass of confined liquid is transmitted undiminished in all directions throughout the liquid. ” Equation for Pascal’s Principle: AY AY Problems: 1. The large piston in a hydraulic lift has an area of 250 com. What force must be applied to the small piston with an area of 25 com in order to raise a car of mass 1 500 xv 2.
A trash compactor pushes down with a force of 500 N on a 3 com input piston, causing a force of 30,000 N to crush the trash. What is the area of the output piston that crushes the trash? 3. When the button of a trash compactor is pushed, a force of 350 N pushes down on a 1. 3 com input piston, creating a force of 22,076 N to crush the trash. What is the area of the piston that crushes the trash? 4. Mr.. Sharron is raising a keg car on his hydraulic lift. If the area of the input piston is CACM, while the area of the output piston is 630 com, what force must be exerted on the input piston to lift the car?
II. Buoyancy: apparent loss of weight of objects – net upward force exerted by the fluid – causes floatation > when FEB. is greater than the – constant throughout the same fluid – increases when density of fluid increases weight of the object – equal to the difference of weight of object in air and weight of object in liquid Problem: 1. The weight of the object is 3 N. It is placed in a tan of water. The water exerts 5 N net upward force on the object. Will the object float? 2. A block of metal weighs 5 N when suspended in air. When placed in water, it weighs 3 N. How much buoyant force acts on the metal?
Will the object float? Ill. Archimedes’ Principle: States that the buoyant force acting on the object submerged in a certain fluid is equal to the weight of the displaced fluid Volume of displaced fluid = volume of the object Immersed: part of the object is in fluid Submerged: total body of the object is in fluid Examples: 1. The buoyant force acted upon by the fluid is 14 N. What is the value of the weight of the object? What is the value of the weight of the displaced fluid? 2. When a block of wood is immersed in a basin of water, the weight of the displaced water is 2 N. How much is the buoyant force acting on the wood? The volume of the metal bar is 1000 com. How much volume of water will be displaced by bar? AN. How much is the buoyant force acting on the wood? IV. Principle of Floatation: A floating object displaces a weight of fluid equal to its own weight Object floats when its density is less than the density of the fluid where it its immersed. Example: bamboo> 300 keg / mm floats in water (-?1000 keg / mm ) v’ Object sinks when its density is greater than the density of the fluid where it its bar of gold> 19 300 keg/ mm sinks in water (-?1000 keg / mm ) Three Rules: 1. Fluid>Abject = FLOAT 2.
Fluid metals> Insulation 2. Convection – Transmission of heat – slows the transfer of heat, not prevent ; Hot air is less dense, it rises. Cold air is denser, it goes down. ; Tendencies of hot air to rise and of cool air to sink > Heaters = near the floor; air-conditioning outlets = near the ceiling – maximum efficiency. 3. Radiation – Transfer of heat through electromagnetic waves – No contact needed – All objects emit radiation depending on their temperature. – The higher the temperature, the greater the amount of energy emitted. ; All substances are capable of absorbing radiation. E cube – continuously emitting radiant energy – melts if an incandescent lamp is focused on it > absorbing a greater amount of heat than it is emitting ; good absorbers are good emitters; poor absorbers are poor emitters ; White or shiny objects reflect most radiant energy and are bad absorbers. Dark, matter, or black objects are good absorbers and poor reflectors. Internal Energy the total energy possessed by a body sum of all the energies possessed by all of the molecules in an object > potential energy due to forces acting on the molecules and due to their separation XIII. Phase Changes: 2.
Condensation -Change of state from gas to liquid 3. Evaporation -Change of state from liquid to gas 4. Melting -Change of state from solid to liquid 5. Freezing/solidification -Change of state from liquid to solid Vaporization ; Change of state from liquid to gas ; Evaporation – vaporization takes place at the surface of liquid ; Boiling – below the surface of a liquid 1) Heat from the sun warms the surface of the water. 2) Some particles of water change state, from a liquid to a gas, due to energy (or heat) from the sun. ) These particles, called water vapor, then rise into the air. XIV.
Temperature: v’ hotness or coldness of a body average value of the kinetic energy of the molecules v’ property of a body >tells the direction of heat flow v’ can be measured using a thermometer v’ instrument for measuring temperature; has thermal sensor and calibrations; v’ Has different scales – Fahrenheit, Celsius and Kelvin v’ Galileo – credited for inventing the first thermometer Temperature Scales: Fahrenheit first created scale among the three v’ based on freezing and boiling point of water 2 OF: freezing point of water 212 OF: boiling point of water Unit : OF Celsius/Centigrade CO – (pure water ) freezing point 100 co – (pure water ) boiling point unit: co Kelvin v’ Introduced the concept of absolute zero >lowest possible temperature >substance has absolutely no energy to give up gases) Unit: K (Kelvin) (WHY? – Kinetic theory of [pick] 1. The weatherman reports that today will reach a high of OFF. Your friend from Sweden asks what is the temperature in degrees Celsius.
What value would you report to your friend? 2. Your parents order an oven from England. The temperature dial on the new oven is calibrated in degrees Celsius. If you need to bake a cake at OFF in the new oven, at what temperature should you set the dial? 3. A German automobile’s engine temperature gauge reads in Celsius, not Fahrenheit. The engine temperature should not rise above about OFF. What is the corresponding Celsius temperature on this car’s gauge? 4. Your grandmother in Ireland sends you her favorite cookie recipe. Her instructions say to bake the cookies at 190. ICC. To what Fahrenheit temperature would you set the oven to bake the cookies? —END I=P/A log 10 (1/10)
