Foundations of Technology Mechanical Advantage

Foundations of Technology Mechanical Advantage
STEMCenter for Teaching & Learning™ Engineering byDesign™ 12/01/2009 Foundations of Technology Mechanical Advantage TITLE SLIDE Teacher Resource – Unit 4 Lesson 1 © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

STEMCenter for Teaching & Learning™ Engineering byDesign™
12/01/2009 The BIG Idea Big Idea: Every system and product is made up of one or more of the nine core technologies: bio-, electrical, electronic, fluid, material, mechanical, optical, structural, and thermal technology. [Authors: Please include teacher notes appropriately.] © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Simple Machines Purpose: Transfer kinetic energy (the energy of motion). Reduce the effort needed to move a load. Change the direction or amount of motion. Change the type of motion. Kinetic energy is the energy possessed by an object (or person) due to its motion or movement. Example – a person running or a ball rolling down the hill is an example of kinetic energy. Example of changing a type of motion – rotary motion input to straight line motion output. Real life example – bicycle tires are rotary motion but the bike moves in a straight line. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Mechanical Advantage Mechanical Advantage (MA): Actual Mechanical Advantage (AMA) Determined by physical measurement of forces. Ideal Mechanical Advantage (IMA) Determined by physical dimensions. Basically mechanical advantage is a measure of how much effort input is decreased by the use of machines. Please note not all machine decrease the input effort. For example a person sweeping a floor requires a greater input force in comparison to the output force (moving dirt). This give you a distance advantage instead. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Mechanical Advantage Actual Mechanical Advantage (AMA): AMA is the ratio of the magnitude of the resistance (R) and effort (E) forces. Friction losses are taken into consideration R = the output force E = the input force The actual mechanical advantage (AMA) is determined by the physical measurement of the input and output forces. The AMA takes into consideration energy loss due to deflection, friction, and wear. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Mechanical Advantage Ideal Mechanical Advantage (IMA): IMA is the ratio of distance traveled by effort and resistance force. IMA is a theory-based calculation Friction losses are not taken into consideration DE = distance traveled by effort force DR = distance traveled by resistance force Ideal mechanical advantage (IMA) is a theory-base calculation. This MA is determined by using measured distances the force traveled for both the input and output forces. IMA is used for efficiency and safety factor design calculations. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Simple Machines A machine is a tool used to complete work with less effort. A simple machine is any device that only requires a single input force to do work. Work is the force (F) applied on an object times the distance (d) traveled by the object. Machines makes work easier. You do work when you exert a force, such a pushing an object over a distance. Machines never change the amount of work done, but they can change the size and direction of the force and the distance. All machines are built from one or more simple machines. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Simple Machines There are Six Types of Simple Machines: Lever Wheel & Axle Pulley [Authors: Please include teacher notes appropriately.] © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Simple Machines There are Six Types of Simple Machines: Inclined Plane Wedge Screw [Authors: Please include teacher notes appropriately.] © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

Simple Machine: Levers
STEMCenter for Teaching & Learning™ Engineering byDesign™ 12/01/2009 Simple Machine: Levers A lever is a rigid bar resting on a pivot (the fulcrum) used to make moving objects easier. Consist of an effort force, load, and fulcrum. There are three types of levers: First Class Second Class Third Class A lever is one of the simplest mechanical devices; it consist of a effort force, load and fulcrum. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

STEMCenter for Teaching & Learning™ Engineering byDesign™ 12/01/2009 Simple Machine: Levers Levers First Class Second Class Third Class The differences between the levers: 1st Class – the fulcrum is located between the load and the effort. 2nd Class – the load is located between the effort and the fulcrum. 3rd Class – the effort is located between the load and the fulcrum. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

STEMCenter for Teaching & Learning™ Engineering byDesign™ 12/01/2009 Simple Machine: Levers First Class Lever MA =1, >1, or <1 Fulcrum is between the load and effort. The effort force and load are applied in the same direction. A pliers is an example of a 1st Class lever. This is the only class lever that can have a MA equal to 1, greater or less than 1. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

STEMCenter for Teaching & Learning™ Engineering byDesign™ 12/01/2009 Simple Machine: Levers Second Class Lever MA >1 The load is between the fulcrum and effort. The resistance force and the effort force are in opposing directions. A wheel barrow is an example of a 2nd Class lever. The MA for a 2nd Class lever is always greater than 1. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

STEMCenter for Teaching & Learning™ Engineering byDesign™ 12/01/2009 Simple Machine: Levers Third Class Lever MA < 1 Effort force is between the fulcrum and load. The resistance force and the effort force are in opposing directions. A fishing rod is an example of a 3rd class lever. The MA for a 3rd Class lever is always less than 1. The effort distance is shorter than the resistance distance. The effort load is greater than the load. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Practice Questions Lever Example Using a 5 ft metal bar and a brick, a park ranger removes a 1200 lb rock from a bicycle path. . Using the bar as a lever, the ranger places the brick 1 ft away from the rock and applies a 300 lb force to the lever. What is the Actual Mechanical Advantage (AMA) of this lever? What is the Ideal Mechanical Advantage (IMA)? Have students identify the type of lever (1st Class) and what information is important in the example word problem (Lever length = 5ft; Load = 1200 lb; Effort force = 300lb; Effort distance = 4ft – the distance of the applied force to the fulcrum; Resistance distance = 1 ft – the distance from the brick (fulcrum) to the rock. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Practice Questions Lever Example Remind the students the difference between AMA and IMA. (The actual mechanical advantage (AMA) is determined by the physical measurement of the input and output forces; Ideal Mechanical Advantage (IMA) is determined by using measured distances the force traveled for both the input and output forces. Explain the diagram and what each force and distance represents. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Practice Questions Lever Example (AMA) Calculation AMA is calculated using the actual forces. Remind students Mechanical Advantage is a unit less number therefore the units cancels out. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Practice Questions Lever Example (IMA) Calculation IMA is calculated using distances. Remind students Mechanical Advantage is a unit less number therefore the units cancels out. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

Simple Machine: Wheel and Axle
STEMCenter for Teaching & Learning™ Engineering byDesign™ 12/01/2009 Simple Machine: Wheel and Axle Wheel and Axle: Is a lever arm that is fixed to a shaft (the axle). The axle and the wheel turns in the same direction. Effort force is applied to the wheel or the axle. The wheel and axle moves together and in the same direction. It is important to identify where the effort force is applied the wheel or the axle. If effort is applied to the wheel it is 2nd Class lever. If it is applied to the axle it is a 3rd Class Lever. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

STEMCenter for Teaching & Learning™ Engineering byDesign™ 12/01/2009 Simple Machine: Wheel and Axle Wheel and Axle: AMA E = the effort force driving the wheel and axle R = the load being driven by the effort The effort force is the force that turns the wheel and axle (the input force) and the load is the resistant load (the output force) © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

STEMCenter for Teaching & Learning™ Engineering byDesign™ 12/01/2009 Simple Machine: Wheel and Axle Wheel and Axle: IMA DE = diameter of effort (wheel or axle) DR = diameter of resistance (wheel or axle) The effort force is the force that turns the wheel and axle (the input force) and the load is the resistant load (the output force) © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

STEMCenter for Teaching & Learning™ Engineering byDesign™ 12/01/2009 Simple Machine: Wheel and Axle Wheel and Axle: Distance traveled Equation for Circumference (C) of a wheel = C = πD D = wheel diameter π = 3.14 Equation for distance traveled (S) = (Circumference{C}) x (# Revolutions) To determine how the linear distance of a wheel, you must find the circumference of the wheel. D is the diameter (radius is equal to D/2). Revolution is the wheel making a complete turn. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Practice Questions Wheel and Axle Example A wheel with a 12 inch radius is used to turn an axle with a radius .5 inches. What is the mechanical advantage? Given the information, only IMA can be calculated. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Practice Questions Wheel and Axle Example A wheel with a 12 inch radius is used to turn an axle with a radius of .5 inches. What is the mechanical advantage? The effort is applied to the wheel, therefore this is a second class lever. Distance of the effort force is equal to 12 inches and the distance to the resistance is equal to 0.5 inches. Reminder – MA is a unit less number. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Practice Questions Wheel and Axle Example If your car has tires with a diameter of 24 inches how many times will the tires rotate if the car travels 100 feet? © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Practice Questions Wheel and Axle Example If your car has tires with a diameter of 24 inches how many times will the tires rotate if the car travels 100 feet? Note: 24 inches needs to be converted to ft. (1 foot = 12 inches) © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

Simple Machine: Pulley
STEMCenter for Teaching & Learning™ Engineering byDesign™ 12/01/2009 Simple Machine: Pulley A pulley is a wheel and axle that support a cable or belt along the wheel’s circumference. Pulleys are used to transfer force or speed and lift loads. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

STEMCenter for Teaching & Learning™ Engineering byDesign™ 12/01/2009 Simple Machine: Pulley Mechanical Advantage: Ideal Mechanical Advantage of a pulley is determined by counting the number of ropes supporting the load to be lifted Actual Mechanical Advantage IMA = the number of strands supporting the load. The end strand ONLY counts when the effort is pointing upward. The AMA = the resistance force (load being lifted) divided by the effort force (input force). © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

STEMCenter for Teaching & Learning™ Engineering byDesign™ 12/01/2009 Simple Machine: Pulley Three types of pulleys Fixed Pulley Movable Pulley Block & Tackle Pulley The fixed pulley MA = 1; the movable pulley MA = 2; the block and tackle pulley is a compound machine, in this example the MA = 4 (the number of ropes uses to move the load) © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Practice Questions Pulley Example The pulley system shown is used to lift a load of 60 lbs a distance of 2’. How much effort must be applied, and how much rope do you need? IMA = the number of strands supporting the load. The end strand ONLY counts when the effort is pointing upward. The AMA = the resistance force (load being lifted) divided by the effort force (input force). Identify the unknown and known information: IMA = 6 (there are 6 ropes and the endpoint rope is pointing upwards); The load (resistance force) = 60 lb; DR = 2 ft (distance of the resistance force). © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Practice Questions Pulley Example IMA = 6 (IMA = AMA) IMA will equal AMA = 6. Find the effort force using the known values. Find the distance the effort force will travel, knowing the distance the resistance force traveled and the IMA. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

Simple Machine: Inclined Plane
STEMCenter for Teaching & Learning™ Engineering byDesign™ 12/01/2009 Simple Machine: Inclined Plane Is a flat surface at an incline (angle), that is used to move heavy objects to a higher level much easier. Examples of an inclined plane: ramp, slanted road, hill. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

STEMCenter for Teaching & Learning™ Engineering byDesign™ 12/01/2009 Simple Machine: Inclined Plane The effort force (E) is parallel to the inclined plane. The load (R) is 900 to the ground; direction of gravity © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

STEMCenter for Teaching & Learning™ Engineering byDesign™ 12/01/2009 Simple Machine: Inclined Plane DE is the distance traveled by the effort = L DR is the distance traveled by the resistance = H L is equal to the length of the slope. H is the height of the inclined plane. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Practice Questions Inclined Plane Example In the diagram below, L = 24 inches, H = 6 inches and the Effort = 60 lb. Find the mechanical advantage and the maximum load that can be moved. What is the tradeoff for reducing the effort? A B H L R E  Identify the known and unknowns: L, H, and E are known; R, IMA and AMA are unknown. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Practice Questions Inclined Plane Example A B H L R E  IMA = AMA. In order to move the 120 lb 6 inches off the ground, we need to travel a distance of 24 inches along the incline. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Simple Machine: Wedge A triangular-shaped tool; tapers to a thin edge. Functions as a moving inclined place. Effort is applied to the top of the height. Effort Inclined Plane Wedge © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Simple Machine: Wedge Used for separating material, raising heavy objects, or tightening spaces. Mechanical Advantage: The effort is applied to the top of the wedge and the resistance force is the caused from the material splitting. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Simple Machine: Wedge Mechanical Advantage: L H © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Practice Questions Wedge Example Find the mechanical advantage and the maximum separation load for a wedge with an incline length of 10 inches, an overall height of 4 inches, and that is exerting an effort of 100 pounds. Identify the known and unknowns: L, H, and E are known; R, IMA and AMA are unknown. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Practice Questions Wedge Example Identify the known and unknowns: L, H, and E are known; R, IMA and AMA are unknown. The maximum load of separation is 250 lb. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Simple Machine: Screw A screw is an inclined plane wrapped around a cylinder, used to create rotary motion or as a threaded fastener Can change a rotary motion into a linear motion The mechanical advantage is large A screw can be an inclined plane wrapped around a cylinder, forming the path and pitch; or a wheel and axle used to create rotary motion. The purpose of a screw is to be used a threaded fastener (tightens two material together); changes a rotary motion into a linear motion. The mechninical advantage for a screw is large. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Simple Machine: Screw Identification: Threaded Information ¼ - 20 UNC 1/4 = the outer diameter of the threads. 20 = the number of threads per inch of screw length. UNC refers to Unified National Coarse thread. © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Simple Machine: Screw Identification: Effort Arm Distance is the length of the wrench Pitch is the distance between threads and linear distance traveled by 1 rotation of the screw Example: If 20 threads per inch, the pitch is 1/20 of an inch © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Simple Machine: Screw Mechanical Advantage: DE is one rotation of the effort arm = Circumference DR is the linear distance traveled during one rotation of the effort arm = pitch © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Practice Questions Screw Example A screw with 18 threads per inch is turned by a screwdriver having a handle diameter of 1 inch. What is the mechanical advantage of the screw? © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

12/01/2009 Practice Questions Screw Example © 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning™ Foundations of Technology © International Technology Education Assoc

Foundations of Technology Mechanical Advantage

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