Work and Six Simple Machines

Work and the Six Simple Machines

"Give me someplace to stand, and I will move the Earth,"

Archimedes

 Simple machines  help us make better use of our muscle power to do work 

 A simple machine produces force  and controls the direction of a force.

Simple machines help us lift, pull or raise items, change the direction of the force, increase the force, split things, fasten things, and cut things.

We all use simple machines every day, opening a door, turning on the water faucet, going up stairs, or opening a can of paint.

Simple machines make work easier.

There are six simple machines.  They are:

1. The Lever
2. The Inclined Plane
3. The Wedge
4. The Screw
5. The Wheel and Axle
6. The Pulley 

Now complete the "Observe and Report" activity below

Remember you can answer questions any way you like...on paper, using a computer or creating a blog, video...

When you finished with the activity you must click on the worksheet with the right mouse button and select "back" to return to this book.  If you close the page with the X on the upper right hand corner, you will need to re-open the book.

http://teacher.scholastic.com/dirtrep/simple/observe.htm

Simple Machines History

What do you think the first simple machine was?

Throughout history, people have learned ways to increase force, change the direction of force, and increase the rate of work  .

We don't actually know what the first simple machine was, but it was probably a large stick used to move heavy objects (rocks).  The lever  .

Or it could be the sharp rock they used to scrape animal skins, the wedge  .

5. Logs were use early in modern building to move huge rocks by rolling them along.  These logs became the wheel and axle around 3000 B.C., and were one of the most important inventions in history.

The inclined plane   and rollers were used in building the great Egyptian pyramids  , one of the Seven Wonders of the World.   2.5 million limestone blocks were moved hundreds of miles over 20 years, weighing 2 to 70 tons each.  Ramps   over one mile long were required to place stones.

The lever, rollers, and pulleys were use to build stonehenge, England. 

 

Watch how one man thinks Stonehenge and other wonders of the world were built using only simple machines and very little else.

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Throughout all the early civilizations, including, Lebanon, Peru, Bolivia, and Easter Island, simple machines were used to build magnificent buildings.  In Lebanon, temples were built with blocks 64 feet long and 13 feet wide, weighing 1,200 tons apiece, a workforce of 25,000 men was required to raise one stone.  The lever, rollers, pulleys, wedges, and the screw were all used early in history.

The industrial revolution was sparked by the invention of the steam engine in Great Britain in the 1700s.   The industrial revolution helped bring people into the machine age and vastly increased the availability of many kinds of products.

Machines enable people to do work with LESS muscle effort and with greater speed.

Want to know more about how the great pyramids were built?  This video show what scientist believe happened based on archeological evidence.

 Work 

What is the Science Definition of Work?

You are doing work when you use a force to cause motion.

Work is the transfer of energy through motion.

In order for work to take place, a force must be exerted through a distance.

Amount of  work done depends on two things:

1. The amount of force (F) exerted.
2. The distance (d) over which the force is applied.

Equation for work -  W = F x d

Work is measured in Joules (N-m) after British scientist James Prescott Joule

One Joule = 1 N-m, = Work done when a force of one Newton acts through a distance of one meter.

There are two factors to keep in mind when deciding whether work is being done:

1. Something has to move.
2. The motion must be in the direction of the applied force.

The amount of work a machine produces equals the force used multiplied by the distance the machine lifts or moves and object.

How does a simple machine make work easier?

    A.  Transferring the force from one place to another.
    B.  Changing the direction of a force
    C.  Increasing the magnitude of a force
    D.  Increasing the distance or speed of a force

Watch the video

Force 

Force is a PUSH or a PULL, that causes a change in the motion or shape of an object. 

Examples:  Push open a door, or shove a book across a desk, or the pull of gravity on a ball when you drop it.

Words to think about that use force – pushing, pulling, stretching, squeezing, bending, and falling.

Forces can be equal – holding a book up in your palm of your hand, or a book laying on the table – Balanced Forces – Your hand or the table pushes up and the book pushes down.

Some types of forces; gravity, electricity, magnetism, and friction.

Whenever an object is caused to move, whether from a standstill or while already in motion, a force is required.

Gravity   is a universal force.  Gravitational force causes every object to attract every other object; a ball falling to the ground; the moon orbiting the Earth.  Every object in the universe exerts a force on every other object; that force is gravity.

watch the video here

Friction  is a force that opposes motion.  Friction occurs when two substances rub together.  Rub your hands together. What did you feel?  Why?  Heat is a byproduct of friction.

The motion of objects is reduced because of friction.  Why do you stop swing on a swing? Why does a ball stops rolling?

Friction can be reduced by smoothing and polishing the surface of contact, by lubricating surfaces with grease or oil, or by using roller  instead of sliding.

Sometimes we want to increase frictional forces – When using the brakes on a bike or car, we are increasing friction  in order to stop.

If there were no friction, your life would be much different.  You wouldn't be able to walk (think about walking on ice) or hold things between your fingers.  You wouldn't be able to turn the pages of a book, or keep your shoes tied, or stop your car with the brakes.

What do you call the force of gravity on your mass?  WEIGHT!  

Two important factors dealing with force are: Mass and Distance, The Earth holds you because it's mass is so large compared to yours, but you do not feel the gravity pull of your neighbor sitting next to you!

Force  is measured in Newtons   and is part of the equation for Work.  W = f x d.

One of the earliest and simplest of machines, a large stick would work as a lever   to move huge rocks.

The lever is essentially a rigid bar that is free to turn about a fixed point called the fulcrum  .

Every Lever has three (3) parts:

1. Resistance Force - What you are trying to move or lift.
2. Effort Force - The work done by the lever.
3. Fulcrum – A fixed pivot point.

Levers are divided into three classes depending on the position of the effort, resistance, and fulcrum. 

First Class Lever

The fulcrum (fixed pivot point) is located between the effort and the resistance forces.  Example - SEESAW.

The effort and the resistance move in opposite directions.  The effort moves down in order to lift the resistance or load.

When the fulcrum is closer to the effort than to the resistance, there is a reduction in force but a gain in speed and distance.

When the fulcrum is closer to the resistance than to the effort, there is a loss in speed and distance, but a gain in force.

When the fulcrum is midway between the effort and the resistance, there is no change in force, speed or distance.

Examples of First Class Levers – seesaw, crowbars, scissors, and claw hammers.

Second Class Levers

The resistance is between the effort and the fulcrum.

The fulcrum is at one end of the lever.

The fulcrum is usually closer to the resistance, (load).

 Second class levers produce a gain in force.

Examples of second class levers – wheelbarrow, bottle openers, and nutcrackers.

Third-Class Levers

The effort is between the resistance and the fulcrum.

The result is usually a loss in force, but a gain in speed and distance.

Examples of third class levers – broom, shovel, baseball bat, and tongs. 

For more details watch the video...

An inclined plane is a sloping surface used to lift heavy loads with relative little effort.  The incline plane does not move.

A surface that is raised at one end.

An inclined plane provides for lesseffort   but NOT less work.  The trade-off is a greater distance to travel.

Allows you to lift a weight you normally couldn't lift to a higher level. example loading ramps.

Increase the elevation of heavy objects without having to lift the object directly.

Examples of inclined planes – simple ramp, escalator, stairs, ladder.

watch the video here

A wedge   is a form of an inclined plane   which can increase a force.  With a wedge, the material (log) remains in place while the wedge moves through it.

A wedge can be one sloping surface like a doorstop. This type is called a single incline plane,   When a wedge has two sloping surfaces, it is called a double incline plane.  An example of this type is the wedge used to split wood for the fireplace.

Wedges can be forced between two things to hold them tightly together, like nails holding two pieces of wood together or a doorstop jammed between the door and the floor to create enough friction to hold the door open.

When sharpened, the wedge can become a knife or an ax.  The tip of a screwdriver (slot head) is a simple wedge.

Wedges can be used to split, cut or fasten.

Examples of wedges are: axe head, log splitter, chisel, knife, nails, doorstop, plows,  screwdriver and scissors

Watch the video

The screw   is another form of an inclined plane.

The screw is an inclined plane wrapped in a spiral   around a cylinder post.

A screw has two parts:

    A. The body – cylinder post

    B. The thread – inclined plane wrapped around the cylinder.

When thinking about a screw think about anything that has threads.

If you look closely at the screw, you'll see that the threads form a tiny “RAMP” that runs around the screw from the tip to near the top.

The pitch of a screw is the distance between two consecutive threads.

One function of the screw is to fasten things – the standard screw or nuts & bolts.

Drill bits are a screw used to make holes.

Airplane propellers, helicopter blades, and fan blades are screws that screw through the air.

Propellers on boats screw through the water.

Most every machine built requires the use of some form of screw to fasten it together.

Imagine you are driving a screw into a board.  As you turn the screw, the threads seem to “PULL” the Screw into the wood.  The wood seems to “SLIDE” up the inclined plane.  Actually, the plane slides through the wood. 

Watch the video here

The wheel and axle   was first used around 3000 B.C. and is one of the most important invention in history.

The wheel and axle is a wheel connected to a rigid pole.

Rollers   were the forerunner the wheel, several logs placed under a heavy object.

The wheel and axle is basically a modified lever  , the center of the axle serves as a fulcrum – making the wheel a lever that rotates around in a circle.

Effort force is applied to a large wheel to turn the smaller axle.

Examples of a wheel and axle -  door knobs, screwdrivers (the whole screwdriver), water faucets, handlebars on a bike, airplane propellers, helicopter blades, fan blades, wheels on a car.

Gears are a modified or special wheel and axle.

A gear is a wheel with teeth along its circumference.

Effort   is exerted on one of the gears, causing the other gear to turn.

In most gears, the larger gear is the effort gear turning a much smaller gear, (the resistance).

Examples of gears – bike sprockets, can opener.

A pulley   is a grooved wheel that turns around an axle (fulcrum), and a rope or a chain is used in the groove to lift heavy objects.

A pulley changes the direction of the force – instead of lifting up, you can pull down using your body weigh against the resistance (load, that you are lifting).

A pulley may be fixed, movable, or used in combination.

The simple pulley   gains nothing in force, distance or speed, but it changes the direction of the force.

A fixed pulley    (attached to something that doesn't move such as the ceiling or wall) acts as a first-class lever with the fulcrum located at the axis, instead of a bar the pulley uses a rope.

A movable pulley   acts as a second -class lever, the load (resistance) is between the fulcrum and the effort.

Examples of pulleys in use – on top of the flag pole, to hoist a sail, to open curtains or mini-blinds, to lift hay into a hayloft.

For more details view the video

Activities

Answer the following questions and activities in any manner you wish. You may want to use a computer, pen and paper, or record your own voice.  Any method is fine.

Remember you can use this digital book or your textbook for help.

Work Input and Work Output

Using any simple machine takes extra work. Yet, the machine can make the work easier to do. Read "the Effects of Friction" on page 284 of the textbook to expand on this idea.

 Simple machines do not decrease the amount of work. In fact, you actually end up doing more work with a machine.

1 List three reasons why people still choose to use machines.

2 All machines need energy to operate.

1. What is the energy source for the simple machines used so far?
2. Suggest three additional energy sources that could be used to do work with simple or complex machines.

Watch the following honda commer cial

This ad is famous because it took 86 attempts before everything went perfect.  It was all shot in one take. There is no special effect of any kind.  Think of all the simple machines being used to create this ad.

At one point, tires are rolling up a ramp!  Can you think of ways to make that happen?  Watch the video closely to answer the following questions.

List 5 simple machines that are being used and where

Simple Machine Where in the ad/what's happening

1_________________________________________________

2_________________________________________________

3_________________________________________________

4_________________________________________________

5_________________________________________________

Still having fun?  Try the following activities.  You can print them out or complete them in some other way that you prefer.

After clicking on the link, use your mouse right-click button and the "back" selection to return to this page.

If simple machines weren't around activity

http://www.teach-nology.com/worksheets/science/simpmach/if/

word search activity

http://www.teach-nology.com/worksheets/science/simpmach/search/

printable word definitions list

http://www.teach-nology.com/worksheets/science/simpmach/vocab/

video review 1

video review 2

 video review 3

The science gizmo is a tool that allows you to practice working with the different elements of work, calculating input effort, output effort, mechanical advantage and speed ratio. This site requires a login from your teacher.  When you have completed the activities to this point, contact your teacher for the science gizmo activity.

There are 3 self-check quiz/puzzles that are also password protected and need to be released by your teacher.  When these are completed, congratulations, you have completed all the elements of this interactive activity.