Simple Machines

What are the 6 simple machines? Inclined plane Wedge Screw Lever Wheel & Axle Pulley

MACHINE Def: A device that allows you to do work in a way that is easier. Sent.: They have agreed to rely primarily on the use of the six simple machines to accomplish their mission.

MACHINE Sp: máquina Discuss in your group different machines.

HOW DOES A MACHINE MAKE WORK EASIER? Change the amount of force you exert Change the distance over which you exert your force. Change the direction in which you exert your force.

MECHANICAL ADVANTAGE Def.: Number of times a machine increases a force exerted on it. Sent.: The mechanical advantage of a machine without friction is called the ideal mechanical advantage, or IMA. Sp.: ventaja mecánica

Simple Machines

Inclined Plane

Def.: Flat, sloped surface Sent.: An inclined plane allows you to exert your input force over a longer distance. Sp.: plano inclinado Discuss with your table different types of ramps.

Inclined Plane How it works: increases the distance the input force has to go. IMA = length of incline ÷ height of incline

Wedge

Taper Def.: to become smaller or thinner toward one end.. Sent.: A wedge is a device that is thick on one end and tapers to a thin edge on the other end Sp.: disminución gradua What are different things that taper?

Wedge Def.: a device that is thick on one end and tapers to a thin edge on the other end. Sent.: That force pushes the wedge down into the wood. Sp.: cuña With your table make a list of at least 5 different wedges. Raise your hand when you have your list.

Wedge Two inclined planes back to back How it works: The wedge moves exerting an output force at a 90° angle IMA = length of wedge ÷ width of wedge

Screw

Thread Def.: a helical groove in a cylindrical hole ( female thread ), formed by a tap or lathe tool, or a helical ridge on a cylindrical bar, rod, shank, etc ( male thread ), formed by a die or lathe tool Kid def.: A twisting raised area around a cylinder or inside a round hole.

Thread Sent.: Record the effort force, the distance lifted and the thread density for 5 tests Sp.: tema Discussion: Is a screw with threads closer together have a higher or lower thread density?

Screw Def.: An inclined plane wrapped around a cylinder creating spirals called threads. Sent.: Like a wedge, a screw is a simple machine that is related to the inclined plane. Sp.: tornillo Discussion: Are there different types of screws? If so, what are they?

Screw How it works: Threads increase the distance over which you exert input force. The output force pulls the screw into the material. Friction holds it in place. IMA = length around the threads ÷ length of screw

Levers

Lever Def: A rigid bar that is free to pivot (rotate.) Kid Def.: A stiff bar that can rotate freely Sent.: What are the advantages of using a lever to lift this stone? Sp.: palanca Disc.: What levers do you use every day?

Fulcrum Def.: The fixed point that a lever pivots around. Sent.: Predict fulcrum placements which will not be successful. Sp.: fulcro Disc.: What types of things can be a fulcrum?

Load Def.: The amount of force the machine provides. Sent.: Label the load, fulcrum and effort force for each example of a lever. Sp.: cargamento

3 Types of Levers

1st Class Lever How it works: Changes direction of input force If fulcrum is closer to output force, also increases force. If fulcrum is closer to input force, also increases distance. Calculating IMA:

1st Class Lever Ex. paint can opener, scissors

2nd Class Lever How it works: Increases force but doesn’t change direction. Calculating IMA:

2nd Class Lever Ex.: Wheel barrow, doors, nutcrackers

3rd Class Lever How it works: Increases distance but doesn’t change direction. Calculating IMA:

3rd Class Lever Ex. Hockey stick, shovel, fishing pole

Wheel & Axle

Radius Def.: a straight line extending from the center of a circle or sphere to the circumference or surface Sent.: As the radius of the wheel increases, what happens to its circumference? Sp.: radio

Wheel & Axle Def.: Made of 2 circular/cylindrical objects fastened together that rotate around a common axis. Object with larger radius is wheel, and smaller radius is axle.

Wheel & Axle How it works: Increases your force by going a longer distance. Calculating IMA: IMA = radius of wheel ÷ radius of axle Ex.: door knob, car wheel & axle, steering wheel, windmill, water wheel

Wheel & Axle

Pulleys

Def.: A grooved wheel with a rope or cable wrapped around it. Sent.: As the number of supporting ropes on the pulley increases, what happens to the length of rope that must be pulled to lift the stone into place? Sp.: polea Disc.: What pulleys have you seen?

Pulleys How it works: Pulling on rope (input force )causes an object to move up. It can decrease the amount of input force needed and it can change direction of input force. IMA = number of sections of rope that support object

Types of Pulleys Fixed – How it works: changes direction of the force Def.: Pulley is attached to an object IMA = 1

Types of Pulleys Movable – How it works: decreases amount of input force needed, doesn’t change direction Pulley isn’t attached IMA = 2

Types of Pulleys Block and Tackle – Def.: made of fixed and moveable pulleys How it works: Decreases amount of input force needed IMA = 3

Compound Machines Def.: A machine that utilizes two or more simple machines. IMA = product of the individual IMA of each simple machine that makes up compound machine.

Simple Machines in the Body At joints are levers - muscles are input force, and output force does the work Teeth are wedges

INPUT FORCE Def.: The force exerted on a machine Sent.: Machines such as the car jack, the ramp, the crow bar, and the claw hammer make work easier by making the output force greater than the input force. Sp.: fuerza aplicada

OUTPUT FORCE Def.: The force exerted on an object by a machine. Sent.: Machines such as the car jack, the ramp, the crow bar, and the claw hammer make work easier by making the output force greater than the input force. Sp.: fuerza desarrollada

INPUT WORK Def.: The work done on a machine as the input force acts through the input distance. Sent.: For such an ideal machine, the input work would equal the output work. Sp.: trabajo aportado

OUTPUT WORK Def.: The work done by a machine as the output force acts through the output distance. Sent.: For such an ideal machine, the input work would equal the output work. Sp.: trabajo producido

Mechanical Advantage = Output force ÷ Input force

If the machine increases force then the mechanical advantage will be greater than 1.

If the machine increases distance then the mechanical advantage will be less than 1.

If the machine changes the direction then the mechanical advantage will be 1.