3Basic ConceptsList the six simple machines and give an example of each.List three types of gears.Name the two primary characteristics of power.Identify two mechanical transmission devices and describe how each operates.Define mechanical advantage and give an example.Recognize the difference between the ideal mechanical advantage (IMA) and actual mechanical advantage (AMA).
4Intermediate Concepts Discuss force and rate in a mechanical system.Describe the difference between scalar and vector quantities.
5Advanced ConceptsDesign a mechanical system for a specific application.Predict the result of a mechanical system based on knowledge of balanced and unbalanced loads.Calculate the mechanical advantage of a simple machine.Compute the mechanical advantage of compound machines.Solve for the percentage of frictional loss in a mechanical system.
6Mechanical Systems Produce work using one or more machines Machines can change size, direction, and speed of forcesMachines can change type of motion produced
9Levers Rotates around fulcrum Position of fulcrum, load, and input force determines lever classFirst-class leversSecond-class leversThird-class levers
10Pulleys Discs rotating around center axis Operate on principle of leversSeveral pulleys together make block and tackle
11Wheels and Axles Also based on principle of levers Large-diameter wheel and small-diameter axle are attached to each otherCan be used to change size or distance of force
12Inclined Planes Makes use of sloping surfaces Rolling objects up slopes is easier than lifting objectsMuch less force to achieve same result
13Screws Operates on principle of inclined planes Long incline plane wrapped around shaftScrews with more threads per inch have advantagesApply greater forceCreate for surface area to produce friction
14Wedges Consist of two inclined planes placed back to back Often used to split materialsHatchets are wedges that use weight and fast movement to split wood
15Gears Metal wheel with small notches cut into rim Gear sets are made so gear teeth interlock and drive each otherGears can control mechanical power in the same way as belts and pulleysGears change direction of power, speed, and torque
16Quantities of Measurement Scalar quantity represents physical quantity and is expressed by number or unitVector quantities have both magnitude and directionDisplacementVelocity
17Torque Force that produces twisting or turning effect or rotation Two componentsAmount of force applied to lever armRadius of lever arm itselfMeasured using Prony brake
18Horsepower (hp) Rate at which output work is performed Several types of hp ratings:Indicated horsepower (ihp)Brake horsepower (bhp)Frictional horsepower (fhp)
19Net Forces of Balanced and Unbalanced Loads Balanced forces are in state of equilibriumMovement ceases in balanceForces of effort and opposition must be totally balancedUnbalanced loads can be calculated with addition and subtraction
20Transmission of Mechanical Energy Compound machines use two or more simple machinesVariations in simple machines may be usedOperations of industrial machines and transportation vehicles rely on principles of one or more simple machines
21Clutches Connects power source to rest of machine Device is needed so vehicles can remain at rest with engine running, start without stalling, and shift gears while movingOperate on principle of frictionTypes in vehicles are diaphragm clutch and centrifugal clutch
22Pulleys and Belts Many belts move around pulleys in vehicles Transmit power from engine to drive engine components, such as water pump and fanControl mechanical energy through five different arrangements
23Chains and Sprockets Found on bicycles, mopeds, and motorcycles Usually used as drive system to bring power to driving wheel of vehicleProvide positive power transfer, which means chain cannot slip like belt on pulley
24Shafts and BearingsShafts are vital parts of automobile engines and drive systemsBearings are made to be strong and allow shaft to turn inside themShafts are not easily bent, so universal joints are used when flexibility is needed
25Mechanical Advantage Simple machines can gain mechanical advantage LeversPulleysWheels and axlesInclined planesWedgesGears
26Ideal Mechanical Advantage vs. Actual Mechanical Advantage Ideal mechanical advantage (IMA)Actual mechanical advantage (AMA)Accounts for loss of energy through frictionFriction is heat energy that is common by-product of mechanical energyAMA is always less than IMA because IMA assumes for 100% efficiencyAMA accounts for frictional losses
27What are the six simple machines What are the six simple machines? Levers, pulleys, wheels and axles, inclined planes, screws, and wedges
28What two simple machines also operate on the principle of the lever What two simple machines also operate on the principle of the lever? Pulleys and wheels and axles
29What type of quantity is displacement? Vector quantities
30Actual mechanical advantage (AMA) The ratio of the increase of force or distance by a machine, including energy lost through friction.BearingA specially shaped piece of metal used to support shafts and reduce friction between metal parts as they move past or revolve around each other.Brake horsepower (bhp)The amount of power available at the rear of the engine under normal conditions.ClutcheA mechanical device that connects the power source to the rest of the machine.
31Frictional horsepower (fhp) DisplacementA vector quantity that includes both distance and direction.First-class leverA lever that has the fulcrum positioned between the input force and the load.Frictional horsepower (fhp)The amount of hp necessary to overcome the internal friction of an engine and other forms of frictional loss.FulcrumThe fixed point around which a lever rotates.
32Ideal mechanical advantage (IMA) A ratio of the forces or the distances involved in a mechanism. It assumes 100% efficiency.Inclined planeA simple machine that makes use of sloping surfaces.Indicated horsepower (ihp)The maximum potentional hp produced by an engine under ideal conditions.LeverA rigid bar that rotates around one fixed point.
33Prony brake Pulley Scalar quantity A device used to measure the effort produced by a twisting or turning force. It is based on the principle that if an opposite force equals the effort produced by a spinning object, movement will cease.PulleyA solid disc that rotates around a center axis. It usually has a groove around the outside edge that allows ropes or belts to easily ride around them.Scalar quantityA physical quantity specified by the magnitude of the quantity and expressed by a number or unit.
34Screw Second-class lever Shaft Simple machine A simple machine consisting of a very long inclined plane wrapped around a shaft.Second-class leverA lever that has the load placed between the fulcrum and the input force.ShaftA long, cylindrical piece of metal used to transfer mechanical energy in many types of machines.Simple machineA lever, a pulley, a wheel and axle, an inclined plan, a screw, or a wedge.
35Third-class lever Universal joint Vector quantity Velocity A lever that has the input force positioned between the fulcrum and the load.Universal jointA joint that allows connected shafts to spin freely, while permitting a change in direction.Vector quantityA quantity that has both magnitude and direction.VelocityA vector quantity that includes speed and direction.
36WedgesA simple machine based on the principle of the inclined plane.Wheel and axleA large-diameter wheel and its small-diameter axle are attached to each other to move as one unit.