REV. February 24, 2009 DRILL 1. Get out U3D Test Review Homework and go over with a partner. 2. Tomorrow’s test will cover the following topics: Mechanical Technology Engineering Design Process Simple Machines and Engineering Problems Input-Output Mechanisms Mechanical Advantage Efficiency and Work

Engineering Design Process U3d-L1 Engineering Design Process Defining a problem Researching and generating ideas Brainstorming Identifying criteria and specifying constraints Exploring possibilities Selecting an approach Developing a design proposal Making a model or prototype Testing and evaluating the design, using specifications Refining the design Creating or making it Communicating processes and results

Problem Solving: Sketch a diagram on the RIGHT SIDE List the given info on the LEFT SIDE Write equation/formula (rearrange if necessary) Substitute and Solve Check your answer, then CIRCLE/BOX ANSWER

F = ? L = 45 lbs.

F = ? L = 75 lbs.

F = ? L = 150 lbs.

U3d-L1 F x d = W Wo / Wi = Eff

U3d-L3 1. A hot air balloon carries 200 lbs cargo, 150 lbs human, and 200 lbs materials up a distance of 2,000 feet. How much work did the balloon do (keep all units)? 1. F x d = W 550 lbs x 2,000 ft = W = 1,100,000 ft-lbs. 2. F x d = W 150 lbs x d = 30,000 ft-lbs. 150 lbs. 150 lbs. d = 200 ft. A physical therapy doctor told his 150-lb patient to do 30,000 ft-lbs of work each day to rehabilitate his leg. The patient decides to climb a hill to perform this work. How high does the patient need to climb in order to meet his goal?

Output = 320 miles Input = 32 gallons Efficiency = ? U3d-L2 1. You have a dog that weighs 50 pounds. You carry her up the stairs a total vertical height of 9 feet. How much work did you do (keep all units)? F x d = W 50 lbs x 9 ft = W = 450 ft-lbs. 2004 Hummer H2 Output = 320 miles Input = 32 gallons Efficiency = ? 3. 2004 Toyota Prius Output = 500 miles Input = 10 gallons Efficiency = ?

DRILL (continued) Output = 320 miles Input = 32 gallons Efficiency = ? U3d-L2 DRILL (continued) 2004 Hummer H2 Output = 320 miles Input = 32 gallons Efficiency = ? 3. 2004 Toyota Prius Output = 500 miles Input = 10 gallons Efficiency = ? Wo / Wi = Eff 320 mls / 32 gal = Eff = 10 mpg Wo / Wi = Eff 500 mls / 10 gal = Eff = 50 mpg

Identify which Core technology is represented by the examples below: U3d-L4 Identify which Core technology is represented by the examples below: Door latch e. Crankshaft Thermostat f. Cylinder Fan g. Battery Light bulb h. Gas tank Mechanical Electronic Mechanical/Thermal Optical Mechanical Structural Electrical

MECHANICAL TECHNOLOGY U3d-L1 MECHANICAL TECHNOLOGY The technology of putting together mechanical parts to produce, control, and transmit motion. Example applications: Gear systems in a car transmission, Brakes on a bicycle, Agitator in a washing machine, Latch on a door. Springs in vehicle shocks

U3d-L1 Input - Output Machines are artifacts that transmit or change the application of power, force, or motion. What is an artifact? something created by humans usually for a practical purpose. Machines can be simple or complex Complex machines are comprised of…. Inputs go in Outputs come out Simple Machines

SIMPLE MACHINES 1. COMPONENTS: Levers Pivot Points Linkage Joints U3d-L1 SIMPLE MACHINES 1. COMPONENTS: Levers Pivot Points Linkage Joints INPUT

U3d-L1 CLASSWORK/HOMEWORK INSTRUCTIONS: Transmit the given input motion to the desired output motion using only the allowed components. Correctly copy the following onto the remaining 2” x 2” boxes in your notebook. input input 2. 3. 4. input input input 5. 6.

PRINCIPLE OF THE LEVER LEVER Lever Wheel and Axle Pulley U3d-L4 PRINCIPLE OF THE LEVER LEVER 3 Categories of simple machines based on the principle of the LEVER: Lever Wheel and Axle Pulley

PRINCIPLE OF THE LEVER 1st 2nd 3rd LEVER Lever Arm Fulcrum U3d-L4 PRINCIPLE OF THE LEVER LEVER Lever Arm Fulcrum Applied Force Load 3 different Classes of levers: 1st 2nd 3rd

PRINCIPLE OF THE LEVER LEVER Which is 1st class? 1st class: U3d-L4 PRINCIPLE OF THE LEVER LEVER 1st class: The fulcrum is between the load and the effort force Which is 1st class?

PRINCIPLE OF THE LEVER LEVER Which is 2nd class? 2nd class: U3d-L4 PRINCIPLE OF THE LEVER LEVER 2nd class: The load is between the effort and the fulcrum Which is 2nd class?

PRINCIPLE OF THE LEVER LEVER Which is 3rd class? 3rd class: U3d-L2 PRINCIPLE OF THE LEVER LEVER 3rd class: The effort is placed between the load and the fulcrum Which is 3rd class?

U3d-L4 LEVERS Notice the direction of motion of the Force and Load for each of the 3 classes of lever.

A B Demonstrate it Sketch the pictures below and answer the questions: U3d-L5 Sketch the pictures below and answer the questions: Which lever would be easier to push down, A or B? Which load will travel the greater distance, A or B? A B Demonstrate it

SIMPLE MACHINES LEVER INCLINED PLANE U3d-L5 SIMPLE MACHINES Principle: a law of nature underlying the working of an artificial device Simple machines work on 2 basic principles: LEVER INCLINED PLANE

LEVERS Which class is the lever below? Describe it. SECOND CLASS U3d-L5 LEVERS Which class is the lever below? Describe it. THIRD CLASS SECOND CLASS FIRST CLASS

PRINCIPLE OF THE LEVER WHEEL-and-AXLE A shaft attached to a disk U3d-L5 PRINCIPLE OF THE LEVER WHEEL-and-AXLE A shaft attached to a disk

2nd Class PRINCIPLE OF THE LEVER WHEEL-and-AXLE Which class of lever? U3d-L5 PRINCIPLE OF THE LEVER WHEEL-and-AXLE Which class of lever? 2nd Class

3rd Class PRINCIPLE OF THE LEVER WHEEL-and-AXLE Which class of lever? U3d-L5 PRINCIPLE OF THE LEVER WHEEL-and-AXLE Which class of lever? 3rd Class

1st Class PRINCIPLE OF THE LEVER PULLEYS U3d-L5 PRINCIPLE OF THE LEVER PULLEYS Pulleys are grooved wheels attached to an axle. Generally, what class lever do they act as? 1st Class

FORCE/DISTANCE MULTIPLIERS U3d-L5 PRINCIPLE OF THE LEVER FORCE/DISTANCE MULTIPLIERS Simple Machines can be: Force Multiplier: Increases the force applied to the work at hand Distance Multiplier: Increases the distance the load moves

FORCE/DISTANCE MULTIPLIERS U3d-L5 PRINCIPLE OF THE LEVER FORCE/DISTANCE MULTIPLIERS From the drill: Which is the force multiplier? In other words, which arrangement gives you greater strength A B

FORCE/DISTANCE MULTIPLIERS U3d-L5 PRINCIPLE OF THE LEVER FORCE/DISTANCE MULTIPLIERS From the drill: Which is the distance multiplier? In other words, which arrangement gives you greater distance A B

F L DL DF DF DL L F FORCE MULTIPLIERS MECHANICAL ADVANTAGE M.A.= = U3d-L8 FORCE MULTIPLIERS MECHANICAL ADVANTAGE F L DL DF MA is the number of times a mechanical device multiplies the Applied Force DF DL M.A.= L F = There are no units – it’s a ratio What are the units for MA? For All Lever Classes

You now have 2 equations: U3d-L8 FORCE MULTIPLIERS You now have 2 equations: L x DL = F x DF DF L DL F = Hint: They’re really the same equation rearranged

QUIZ REVIEW Machines are… What is an artifact? U3d-L8 QUIZ REVIEW Machines are… artifacts that transmit or change the application of power, force, or motion. What is an artifact? something created by humans usually for a practical purpose. Machines can be simple or complex Complex machines are comprised of…. Simple Machines

Circumference = Pi * Wheel diameter U3d-L8 PRINCIPLE OF THE LEVER WHEEL AND AXLE M.A. = Radius (D) to Force (F) = DF Radius (D) to Load (L) DL Rotary Motion the circular motion which occurs when the wheel and axle are rotated about the centerline axis. Linear Motion the straight-line motion which occurs when a wheel rolls along a flat surface. The linear distance traveled when the wheel completes one revolution is equal to the circumference of the wheel. Circumference = Pi * Wheel diameter

PRINCIPLE OF THE LEVER PULLEY U3d-L8 PRINCIPLE OF THE LEVER PULLEY A pulley is an adaptation of a wheel and axle. A single pulley simply reverses the direction of a force. When two or more pulleys are connected together, they permit a heavy load to be lifted with less force. The trade-off is that the end of the rope must move a greater distance than the load.

PRINCIPLE OF THE LEVER PULLEY MA = L / F U3d-L8 PRINCIPLE OF THE LEVER PULLEY M.A. = Total number of strands supporting the load MA = L / F

PRINCIPLE OF THE LEVER PULLEY 1 1 100 U3d-L8 PRINCIPLE OF THE LEVER PULLEY Fixed Pulley – when a pulley is attached or fixed to a strong member, which will not move. How many strands are supporting the load? What is the MA of a fixed pulley? How many lbs of force are required to lift 100 lbs of load? When a fixed pulley is used, the force needed to lift a weight does not change. 1 1 100

PRINCIPLE OF THE LEVER PULLEY U3d-L8 PRINCIPLE OF THE LEVER PULLEY Movable Pulley – splits the work in half. How many strands are supporting the load? What is the MA of a movable pulley? How many lbs of force are required to lift 100 lbs of load? When a movable pulley is used, the force needed to lift a load is half that of the load. 2 2 50

PRINCIPLE OF THE LEVER PULLEY U3d-L8 PRINCIPLE OF THE LEVER PULLEY Block and Tackle – a system of three pulleys How many strands are supporting the load? What is the MA of a movable pulley? How many lbs of force are required to lift 120 lbs of load? When a block and tackle is used, the force needed to lift a load is 1/3 that of the load. 3 3 40

PRINCIPLE OF THE INCLINED PLANE U3d-L8 PRINCIPLE OF THE INCLINED PLANE INCLINED PLANE 3 Categories of simple machines based on the principle of the INCLINED PLANE: Inclined Plane Wedge Screw

PRINCIPLE OF THE INCLINED PLANE U3d-L8 PRINCIPLE OF THE INCLINED PLANE Inclined Plane – sloped surfaces used to make a job easier Easier to go up a slope than a vertical surface Wedge – used to split, separate, and grip Wood chisel, firewood axe, doorstop Screw – an inclined plane wrapped around a shaft 1/2-inch x 12 machine screw ½” diameter 12 threads per inch

PRINCIPLE OF THE INCLINED PLANE U3d-L8 PRINCIPLE OF THE INCLINED PLANE The inclined plane is the simplest machine of all the machines. An inclined plane is a flat sloping surface along which an object can be pushed or pulled. An incline plane is used to move an object upward to a higher position. M.A.= Distance = D Height H H D L F

PRINCIPLE OF THE INCLINED PLANE U3d-L8 PRINCIPLE OF THE INCLINED PLANE During its use, an inclined plane remains stationary, while the wedge moves. With an inclined plane the effort force is applied parallel to the slope of the incline. With a wedge the effort force is applied to the vertical edge (height) incline. FORCE FORCE

PRINCIPLE OF THE INCLINED PLANE U3d-L8 PRINCIPLE OF THE INCLINED PLANE FORCE FORCE D H M.A.= D D H H