U3d-L6 Complete back of your 3D worksheet.

2 ft 2 ft U3d-L7 2.A gardener is capable of applying 50 lbs. to lift a wheelbarrow. His hands are placed 4 feet from the axle of the wheelbarrow. The weight of the compost that he carries is 2 feet from the axle of the wheelbarrow. What is the maximum weight of compost he can carry? CLASSWORK REVIEW L = DL = F = DF = ? 2 ft. 50 lbs. 4 ft. L x DL = F x DF L x 2 ft = 50 lbs x 4 ft L x 2 ft = 200 ft-lbs L = 100 lbs.

3.A water pump at the State Park is set up as a 3rd-class lever. The load that the suction inside the pump weighs is 20 lbs. The distance from the load to the fulcrum is 18 inches. The Park Ranger is wondering if it is possible for a child with 15 lbs. of strength to lift the pump lever. She is also wondering where an adult who can apply a force of 30 lbs. should put their hand to lift it. Help her out! SO CAN THE CHILD LIFT IT AS DESIGNED? U3d-L7 CLASSWORK REVIEW This problem is asking 2 questions. What are they? L = DL = F = DF = 20 lbs. 18” 15 lbs. ? 15 lbs 15 lbs L x DL = F x DF 20 lbs x 18” = 15 lbs x DF 360 in-lbs = 15 lbs x DF DF = 24” DL = 18” DF = 24”

U3d-L7 CLASSWORK REVIEW L = DL = F = DF = 20 lbs. 18” 30 lbs. ? 30 lbs 30 lbs L x DL = F x DF 20 lbs x 18” = 30 lbs x DF 360 in-lbs = 30 lbs x DF DF = 12” DL = 18” DF = 12” 3.A water pump at the State Park is set up as a 3rd-class lever. The load that the suction inside the pump weighs is 20 lbs. The distance from the load to the fulcrum is 18 inches. The Park Ranger is wondering if it is possible for a child with 15 lbs. of strength to lift the pump lever. She is also wondering where an adult who can apply a force of 30 lbs. should put their hand to lift it. Help her out!

Where have you seen an inclined plane used before? December 11, 2009 DRILL U3d-L7

1.To understand and calculate Mechanical Advantage (MA) for various simple mechanisms 2.To review 3D Quiz 2 3.To know and apply the three simple mechanisms based on the inclined plane TODAY’S OBJECTIVES U3d-L8

U3d-L7 1.Get out your Unit 3D Mechanical Technology problem sheet. 2.Homework-study for the quiz tomorrow. Topics covered: 1.3 Classes of Levers and examples 2.Force and Distance Multipliers 3.Engineering Problems DRILL DECEMBER 14, 2009 CLOSED-NOTES QUIZ TOMORROW, IF WE ARE QUIET! REVIEW TODAY FOR QUIZ TOMORROW!

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

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

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 U3d-L8

Simple machines work on 2 basic principles: LEVER INCLINED PLANE Principle: a law of nature underlying the working of an artificial device U3d-L8

There are 3 classes of lever: Third Class U3d-L8

1.A 1st-class lever is used to lift a bureau that weighs 80 lbs. The bureau is located 3 feet from the fulcrum. A child who applies the force to the other side of the lever has only 20 lbs. of strength to push. How far from the fulcrum should the child apply the force? (HINT: Sketch a picture, list the given information, write your equation, and solve for the unknown) 80 lbs. 3 ft.DF = ? F = 20 lbs. L = 80 lbs. DF = ? DL = 3 ft. F = 20 U3d-L8

80 lbs. 3 ft.DF = ? F = 20 lbs. L = 80 lbs. DF = ? DL = 3 ft. F = 20 L x DL = F x DF 80 lbs x 3 ft = 20 lbs x DF 240 ft-lbs = 20 lbs x DF 20 ft 20 ft DF = 12 ft U3d-L8

80 lbs. 3 ft.DF = ? F = 20 lbs. L = 80 lbs. DF = ? DL = 3 ft. F = 20 DF = 12 ft What is the Mechanical Advantage of this lever? DF DL M.A.= 12 ft. 3 ft. = 4 = U3d-L8

80 lbs. 3 ft.DF = ? F = 20 lbs. L = 80 lbs. DF = ? DL = 3 ft. F = 20 lbs. DF = 12 ft MA = 4 What does F x MA = ? L U3d-L8

2 ft 2 ft 2.A gardener is capable of applying 40 lbs. to lift a wheelbarrow. Her hands are placed 3 feet from the axle of the wheelbarrow. The weight of the compost that she carries is 2 feet from the axle of the wheelbarrow. What is the maximum weight of compost she can carry? L = DL = F = DF = ? 2 ft. 40 lbs. 3 ft. L x DL = F x DF L x 2 ft = 40 lbs x 3 ft L x 2 ft = 120 ft-lbs L = 60 lbs. U3d-L8

80 lbs. 3 ft.DF = ? F = 20 lbs. L = 60 lbs. DF = 4 ft. DL = 2 ft. F = 30 lbs. What is the Mechanical Advantage of this lever? DF DL M.A.= 4 ft. 2 ft. = 2 = U3d-L8

This problem is asking 2 questions. What are they? L = DL = F1 = DF = 20 lbs. 20” 25 lbs. ? 25 lbs 25 lbs L x DL = F x DF 20 lbs x 20” = 25 lbs x DF 400 in-lbs = 25 lbs x DF DF = 16” DL = 20” DF = 16” 3.A water pump at the State Park is set up as a 3rd-class lever. The load that the suction inside the pump weighs is 20 lbs. The distance from the load to the fulcrum is 20 inches. The park ranger is wondering where an adult who can apply a force of 25 lbs. should put her hand to lift the pump. The ranger is also wondering where another adult who can apply a force of 10 lbs. should put her hand to lift the pump. U3d-L8

L = DL = F1 = DF = 20 lbs. 20” 10 lbs. ? 10 lbs 10 lbs L x DL = F x DF 20 lbs x 20” = 10 lbs x DF 400 in-lbs = 10 lbs x DF DF = 40” DL = 20” DF = 40” 3.A water pump at the State Park is set up as a 3rd-class lever. The load that the suction inside the pump weighs is 20 lbs. The distance from the load to the fulcrum is 20 inches. The park ranger is wondering where an adult who can apply a force of 25 lbs. should put her hand to lift the pump. The ranger is also wondering where another adult who can apply a force of 10 lbs. should put her hand to lift the pump. U3d-L8

U3d-L7 CLOSED-NOTES QUIZ TALKING WILL RESULT IN A GRADE OF ZERO!

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 U3d-L8 WHEEL AND AXLE

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. U3d-L8 PULLEY

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

3 Categories of simple machines based on the principle of the INCLINED PLANE: INCLINED PLANE Inclined PlaneWedgeScrew U3d-L8

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 U3d-L8

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. H D L F M.A.= Distance = D Height H

U3d-L8 FORCE 1.During its use, an inclined plane remains stationary, while the wedge moves. 2.With an inclined plane the effort force is applied parallel to the slope of the incline. 3.With a wedge the effort force is applied to the vertical edge (height) incline.

U3d-L8 DHDH M.A.= FORCE D D H H

U3d-L8 Complete the Simple Mechanism Problems worksheet