Simple machines and mechanisms Lesson 5.0 and 5.1 Pages 126-143.

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Simple machines Simple machines and mechanisms and mechanisms Lesson 5.0 and 5.1 Lesson 5.0 and 5.1 Pages 126-143 Pages 126-143

Transcript of Simple machines and mechanisms Lesson 5.0 and 5.1 Pages 126-143.

Page 1: Simple machines and mechanisms Lesson 5.0 and 5.1 Pages 126-143.

Simple machines and Simple machines and mechanismsmechanisms

Lesson 5.0 and 5.1Lesson 5.0 and 5.1

Pages 126-143Pages 126-143

Page 2: Simple machines and mechanisms Lesson 5.0 and 5.1 Pages 126-143.

What to knowWhat to know

►6 types of simple machines6 types of simple machines►3 classifications of levers3 classifications of levers► Ideal mechanical advantage of simple Ideal mechanical advantage of simple

machines: how to find themmachines: how to find them►What a mechanism is What a mechanism is

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Six simple machinesSix simple machines

►LeverLever►Wheel and axelWheel and axel► Incline plane (ramp)Incline plane (ramp)►ScrewScrew►PulleyPulley►WedgeWedge

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TerminologyTerminology

►MechanismMechanism: is made up of several : is made up of several different types of machines that work different types of machines that work together to perform a specific function. together to perform a specific function.

►Simple machineSimple machine: is a machine that : is a machine that requires the application of a single requires the application of a single force to do work. force to do work.

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LeversLevers

► A A leverlever is a simple machine that changes is a simple machine that changes the amount of force you must exert in order the amount of force you must exert in order to move an object.to move an object.

► There are five components to a lever:There are five components to a lever: The fulcrumThe fulcrum The effort forceThe effort force The loadThe load The effort arm The effort arm The load armThe load arm

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Parts of a leverParts of a lever

Effort arm

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Parts of a leverParts of a lever

► FulcrumFulcrum – supports the lever and is a fixed point. It – supports the lever and is a fixed point. It is the point of rotation.is the point of rotation.

► Effort force Effort force – the force you exert on a lever – the force you exert on a lever

► The load The load – the mass of an object that is being – the mass of an object that is being moved.moved.

► Effort arm Effort arm – the distance between the fulcrum and – the distance between the fulcrum and the effort forcethe effort force

► Load arm Load arm – the distance between the fulcrum and – the distance between the fulcrum and the loadthe load..

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► Class one:Class one: Teeter totterTeeter totter ScissorsScissors

► Class two:Class two: Wheel barrelWheel barrel Bottle openerBottle opener

► Class three:Class three: RakeRake Hockey stickHockey stick

Class of leversClass of levers

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Class of leversClass of levers

► First classFirst class: output force is always in the : output force is always in the opposite direction of the input force.opposite direction of the input force.

► Second classSecond class: input and output forces are : input and output forces are always in the same direction.always in the same direction.

► Third classThird class: input and output are in the : input and output are in the same directions AND the mechanical same directions AND the mechanical advantage is always less than one. advantage is always less than one. They increase speed and distance. They increase speed and distance.

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Ideal Mechanical advantage of a Ideal Mechanical advantage of a leverlever

►Remember MA = output divided by Remember MA = output divided by inputinput

►However, you need an experiment to However, you need an experiment to find this out, so we often find the ideal find this out, so we often find the ideal mechanical advantage – assuming mechanical advantage – assuming friction does not play a huge role. friction does not play a huge role.

►SO:SO: IMA = length of input arm/length of output IMA = length of input arm/length of output

armarm

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Lets try to figure it out. Lets try to figure it out.

1.1. If we have a lever and the input arm If we have a lever and the input arm is 40cm and the length of the output is 40cm and the length of the output arm is 10cm, what is the I.M.A.?arm is 10cm, what is the I.M.A.?

2.2. If the length of the load arm is 4cm If the length of the load arm is 4cm and the length of the effort arm is and the length of the effort arm is 20cm, what is the I.M.A.?20cm, what is the I.M.A.?

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AnswersAnswers

1.1. Input arm / output arm = 40 / 10Input arm / output arm = 40 / 10 Therefore the answer is 4.Therefore the answer is 4. The I.M.A. = 4The I.M.A. = 4

2.2. Input or effort arm/ output or load Input or effort arm/ output or load armarm

20 / 420 / 4 The I.M.A. = 5The I.M.A. = 5

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STOPSTOP

►At this point, lets stop and take notes At this point, lets stop and take notes on levers.on levers.

►Complete learning checkpoint Complete learning checkpoint questions 1-3 on page 135 questions 1-3 on page 135

►Complete handout page 532.Complete handout page 532.

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PulleysPulleys

►A A pulleypulley consists of a grooved wheel consists of a grooved wheel with a rope, cable or chain running with a rope, cable or chain running around it. The pulley is free to rotate.around it. The pulley is free to rotate.

►A pulley can:A pulley can: Change the direction of the forceChange the direction of the force Increase the output force depending Increase the output force depending

upon:upon:►If it is a If it is a fixedfixed or or moveable moveable pulleypulley

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Fixed v. Moveable Fixed v. Moveable

► A A fixed pulleyfixed pulley is attached to a is attached to a stationary object and ONLY changes the stationary object and ONLY changes the direction of the force. It has a direction of the force. It has a mechanical advantage of only one (1). mechanical advantage of only one (1).

►A A moveable pulleymoveable pulley is allowed to move is allowed to move along a rope and increases the input along a rope and increases the input force to get a mechanical advantage of force to get a mechanical advantage of 22 The load is often attached to the pulley.The load is often attached to the pulley.

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I.M.A. of a pulley I.M.A. of a pulley SystemSystem

►The I.M.A. of a pulley system is equal The I.M.A. of a pulley system is equal to he number of to he number of support ropessupport ropes. . See page 137 for pictures. See page 137 for pictures.

►By counting the support ropes, you’ll By counting the support ropes, you’ll know the I.M.A. of the pulley system. know the I.M.A. of the pulley system.

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► The effort arm and load arm on pulley’s are The effort arm and load arm on pulley’s are the same. So how do you achieve the same. So how do you achieve Mechanical Advantage? Mechanical Advantage?

►When you combine fixed and moveable When you combine fixed and moveable pulleys you get pulleys you get block and tackle block and tackle and in the and in the process, create Mechanical Advantage.process, create Mechanical Advantage.

► A A compound pulley compound pulley is made up of several is made up of several pulleys working together. pulleys working together.

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Wheel and AxleWheel and Axle

►A A wheel and axlewheel and axle consists of a shaft or consists of a shaft or axle that is attached to a larger disk, axle that is attached to a larger disk, called the wheel. called the wheel.

Examples: doorknobs, bike pedals, Examples: doorknobs, bike pedals, screwdriverscrewdriver

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I.M.A. of a wheelI.M.A. of a wheel

► If you turn the axle:If you turn the axle: IMA = radius of axle / radius of wheelIMA = radius of axle / radius of wheel

► If you turn the wheel:If you turn the wheel: IMA = radius of wheel / radius of axleIMA = radius of wheel / radius of axle

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Inclined PlanesInclined Planes

►An An incline planeincline plane (ramp) is a sloping (ramp) is a sloping surface on which an object can move. surface on which an object can move.

► It decreases or reduces force but It decreases or reduces force but increases distance.increases distance.

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IMA of an inclined planeIMA of an inclined plane

► IMA = length of ramp / height of rampIMA = length of ramp / height of ramp

Or IMA = l / hOr IMA = l / h

►So and object raised 2m by pushing it So and object raised 2m by pushing it up a ramp 6m long give us and IMA of:up a ramp 6m long give us and IMA of: IMA = l / hIMA = l / h = 6 / 2= 6 / 2 = 3= 3

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ScrewScrew

►A A screwscrew is an inclined plane wrapped is an inclined plane wrapped around a rod. around a rod.

►The part that wraps is called the The part that wraps is called the threadthread..

►The thread is much longer than the rodThe thread is much longer than the rod – – giving it a mechanical advantage similar giving it a mechanical advantage similar to the ramp. to the ramp.

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The wedgeThe wedge

►A A wedgewedge is an inclined plane that is an inclined plane that travels through the object or material. travels through the object or material.

Ie: axe through woodIe: axe through wood Needles, knives, front teethNeedles, knives, front teeth

►The longer and narrower the wedge, The longer and narrower the wedge, the greater the M.A.the greater the M.A.