- Distribute small toy cars that have wheels joined by axles to groups of students. Kick-start a discussion with some questions about the toy car mechanics, such as: How do these toy cars move? How are the wheels on each side of the car joined to each other?
- Have a student volunteer point to the rod that holds the two wheels together. Explain that the bar that joins two wheels is called an axle .
- Tell students that they will be learning about wheels and axles.
- Hold up the doorknob, explaining that it is an everyday example of a wheel and axle.
- Challenge the students to help you identify the wheel and axle in the doorknob. Listen as different students call out their guesses.
- After some speculation, tell students that the knob that turns is the wheel. The inner rod that is attached to the knob is the axle.
- Demonstrate how the wheel and axle works by turning the knob (wheel). That turns the inner rod (axle) and moves the latch, to open the door.
Guided Practice
(15 minutes)- To consolidate student thinking, set up activity stations with play dough and a rolling pin.
- Let students practice flattening the dough with the pin.
- Guide them to express these understandings: The rolling pin is a wheel and axle. When you push on the handles (the axle) the wheel turns and flattens out the dough.
- Challenge students to think of other common machines that have one wheel like the rolling pin. Great examples include a wheelbarrow, a top, and a playground merry-go-round.
Independent working time
(15 minutes)- Pass out a copy of the Wheel and Axle worksheet to each student to complete independently.
- Walk around the classroom to offer support to students who get stuck.
Differentiation
- Enrichment: Have students who need more of a challenge read a history of other simple machines, and fill out an accompanying word search.
- Support: Put students who need more support into pairs to complete the Wheel and Axle worksheet.
Assessment
(10 minutes)- Collect the worksheets that the students have filled out, and correct them using the Wheel and Axle answer sheet.
Review and closing
(5 minutes)- In summary, remind students that the rolling pin is a wheel and axle. When you push on the handles (the axle) the wheel turns and flattens out the dough.
- Challenge students to think of other common machines that have one wheel like the rolling pin, such as a wheelbarrow, top, and merry-go-round.
- Remind your class that the wheel and axle is only one of six common simple machines that help things move. For homework or additional independent work, consider encouraging students to learn more about other kinds of simple machines.
The wheel and axle , the inclined plane , the wedge , the , and the screw . Several of these simple machines are related to each other. But, each has a specific purpose in the world of doing work.
There are special tools for measuring the force necessary to move an object. These are known as force meters. They use a spring and a hook to determine how much pull is required to slide an object up an inclined plane. Really very simple to use.
Compound Machines
Simple machines can be combined together to form compound machines. Many of our everyday tools and the objects we use are really compound machine . Scissors are a good example. The edge of the blades are wedges. But the blades are combined with a lever to make the two blades come together to cut.
A lawnmower combines wedges (the blades) with a wheel and axle that spins the blades in a circle. But there is even more. The engine probably works in combination of several simple machines and the handle that you use to push the lawnmower around the yard is a form of a lever. So even something complicated can be broken down into the simplest of machines.
Take a look around you — can you figure out what simple machines make up a can opener, the hand cranked pencil sharpener, the ice dispenser in the refrigerator or the stapler? Just be careful, though. In our modern times, many things rely on electronics and light waves to function and are not made of simple machines. But even then, you may be surprised. The turntable in your microwave oven is a wheel and axle. The lid to the laptop is connected to the pad by a hinge or lever.
Simple machines may be simple — but they are simply everywhere.
A Word or Two About Rube
Rube Goldberg was a famous cartoonist who lived between 1883 and 1970. His life was spent creating art and sculptures, but his most famous work was for his "inventions." These inventions were a series of simple machines put together in a complex fashion to accomplish something very simple, but it took many steps to get there. Contests have been run for many years since Mr. Goldberg first created his unique ideas. In the contests people try to come up with new ways to turn on a light, or start a toaster using these combinations of the simple machines to wow judges and audiences for their unique way of doing these simple tasks.
Rube Goldberg machines are fun to watch and to build. Visit this site for some fun — see if you can identify each of the simple machines as they work together in this animation of a Rube Goldberg gadget designed to get this guy out of bed in the morning. Click .
For more information about Rube Goldberg"s life and his art, click .
How Simple Machines Work
What is a simple machine and how do they work? I"m so glad you asked! Machines make work easier by changing the size of force, direction of force, or distance the force acts on.
Lifting a car with a flat tire and loosening the lugnuts can be accomplished by a single person thanks to simple machines. The jack and lug wrench are simple machines that alter the force needed to change the tire.
Six Simple Machines
Simple machines are basic devices used to alter the force needed to accomplish a task. There are six types of simple machines.
- lever
- wheel and axle
- inclined plane
- wedge
- screw
- pulley
The first type of simple machine is the lever. A lever is a rigid bar that rotates on the fixed point of a fulcrum and changes the distance or size of a force.
There are three classes of levers. A first class lever has an input force and output force on either side of the fulcrum. This causes the output to move in the opposite direction of the the input force. An example of a first class lever is a see-saw. A second class lever has an output force between the input force and fulcrum. This changes the distance of the force. A wheelbarrow is a second class lever. The third class lever has the input force between the output and fulcrum. A broom is a third class lever.
Wheel and Axle
The wheel and axle make work easier by changing the distance the force acts on. A wheel and axle consists of two disks or
cylinders with different radiuses. Examples are a steering wheel and shaft, a car wheel and axle, and a screwdriver.
Inclined Plane
An inclined plane is a slanted surface on which a force can move an object to a different elevation. Why do gentler slopes and ramps require less energy to move a load on? Because the input force required to travel the greater distance of a slope is changed to the smaller distance of the output force – the upward motion.
A wedge is a device made of two back to back inclined planes and is used to split objects. When a wedge is driven into a log, the size of the input force at the wider top of the wedge is changed to greater output force at the narrower point forcing the wedge through the wood. Knife blades are an example of a wedge.
A screw is an inclined plane wrapped around a cylinder. Screws with threads closer together require
less force to turn because the length of the inclined plane is longer. Nuts and bolts are screws. A nut is a screw with the threads on the inside.
The last type of simple machine is the pulley. A pulley consists of a rope that fits into a groove in a wheel. A pulley makes work easier by changing the direction or direction and size of the force.
There are three types of pulleys . They are the fixed pulley, moveable pulley and pulley system.
The fixed pulley is a single fixed pulley and rope. This changes the output direction of the force, making it opposite of the input. When you pull down on a fixed pulley a weight is lifted up.
A moveable pulley is fixed to the object being moved instead of a fixed location. Moveable pulleys multiply the input force needed to lift a heavy object thus reducing the force needed to lift heavy objects. Moveable pulleys are used to move ship sails and window washer platforms.
Pulley systems combine fixed and moveable pulleys to create large mechanical advantages. A crane uses pulley systems to lift enormous loads like locomotives.
References
- Michael Wysession, David Frank, Sophia Yancopoulos. Physical Science Concepts in Action. p.417 – 435. New Jersey: Prentice Hall, 2004.
A simple machine is a mechanical device that consists of a minimum of moving parts but yet can create an improvement of the output over the input. The improvement could be creating a mechanical advantage or simply changing the direction of the output. Mechanical advantage is the increase of force, distance or speed from the input value.
Around the 16th century, the classic list of simple machines was determined. The list consisted of the lever, wheel and axle, pulley, inclined plane, wedge, and screw.
These simple machines can be broken into three classifications: lever simple machines, rotating simple machines, and inclined plane simple machines.
Questions you may have include:
- What do lever simple machines do?
- What do rotating simple machines do?
- What do inclined plane simple machines do?
This lesson will answer those questions. Useful tool: Units Conversion
Lever simple machines
The lever simply consists of a rod or board that pivots on a fulcrum, creating a mechanical advantage or a change in direction.
The lever is a classic simple machine that achieves a mechanical advantage according to the ratio of the output or load arm of the lever divided by the input or effort arm.
The mechanical advantage of a lever can concern force, distance, or speed of the output.
The efficiency of the lever is very high, since the loss due to friction at the fulcrum is low.
Rotating simple machines
Rotating simple machines include rollers, wheel and axle, crank, and pulley.
Rollers
The wheel or roller by itself can make it easier to move objects by overcoming friction.
Wheel and axle
When an axle is added to a wheel, a torque on the axle increases the speed of the outer surface of the wheel. Likewise, turning the wheel from its outer edge increases the force applied from the axle.
Crank
A crank is like a wheel and axle. You can push on the handle of a crank, and it will create a twisting force or torque on the axle. This is a variation of the wheel and axle.
Pulley
A pulley is a wheel and axle, that uses a rope to lift objects. A major purpose of a pulley is to change the direction of the input force. You can pull down one a pulley rope, and the rope will lift the object upward.
Complex set of pulleys
A complex set up pulleys, such as a block-and-tackle configuration, can result in a mechanical advantage. The question is that if it is a complex set, is it still a simple machine? Probably not.
Inclined plane simple machines
Variations of an inclined plane include a ramp, wedge, and screw.
Ramp
The inclined plane or ramp makes raising a weight to a given height easier, according to the angle of the incline. Unfortunately, the resistive force of friction from sliding the object on the ramp can negate the mechanical advantage.
Variations of the inclined plane are the wedge and screw.
Wedge
Although a wedge is considered a simple machine, it is really a special application of an inclined plane.
Screw
The screw is really an inclined plane that is wrapped around a shaft. Turning the shaft around its central axis transforms rotational motion and torque into axial motion and force.
A screw can also act like a wedge, forcing itself into a softer material.
Summary
Simple machines usually exchange using a smaller force over a greater distance to move a heavy object over a short distance. The work required is the same, but the force required is less. The are also simple machines that help to reduce the resistance of friction or such.
Make it your mission to benefit your community
Topics: Simple machine , Mechanical advantage , Force Pages: 5 (856 words) Published: September 22, 2013
Activity 1.1.2 Simple Machines Practice Problems Answer Key
Procedure
Answer the following questions regarding simple machine systems. Each question requires proper illustration and annotation, including labeling of forces, distances, direction, and unknown values. Illustrations should consist of basic simple machine functional sketches rather than realistic pictorials. Be sure to document all solution steps and proper units.
All problem calculations should assume ideal conditions and no friction loss.
Simple Machines – Lever
A first class lever in static equilibrium has a 50lb resistance force and 15lb effort force. The lever’s effort force is located 4 ft from the fulcrum.
1.Sketch and annotate the lever system described above.
2.What is the actual mechanical advantage of the system?
3.Using static equilibrium calculations, calculate the length from the fulcrum to the resistance force. FormulaSubstitute / SolveFinal Answer
A wheel barrow is used to lift a 200 lb load. The length from the wheel axle to the center of the load is 2 ft. The length from the wheel and axle to the effort is 5 ft.
4.Illustrate and annotate the lever system described above.
5.What is the ideal mechanical advantage of the system?
FormulaSubstitute / SolveFinal Answer
6.Using static equilibrium calculations, calculate the effort force needed to overcome the resistance force in the system. FormulaSubstitute / SolveFinal Answer
A medical technician uses a pair of four inch long tweezers to remove a wood sliver from a patient. The technician is applying 1 lb of squeezing force to the tweezers. If more than 1/5 lb of force is applied to the sliver, it will break and become difficult to remove.
7.Sketch and annotate the lever system described above.
8.What is the actual mechanical advantage of the system?
FormulaSubstitute / SolveFinal Answer
9.Using static equilibrium calculations, calculate how far from the fulcrum the tweezers must be held to avoid damaging the sliver FormulaSubstitute / SolveFinal Answer
Simple Machines – Wheel and Axle
10. What is the linear distance traveled in one revolution of a 36 in. diameter wheel? FormulaSubstitute / SolveFinal Answer
An industrial water shutoff valve is designed to operate with 30 lb of effort force. The valve will encounter 200 lb of resistance force applied to a 1.5 in. diameter axle.
11.Sketch and annotate the wheel and axle system described above.
12.What is the required actual mechanical advantage of the system? FormulaSubstitute / SolveFinal Answer
13.What is the required wheel diameter to overcome the resistance force? FormulaSubstitute / SolveFinal Answer
Simple Machines – Pulley System
A construction crew lifts approximately 560 lb of material several times during a day from a flatbed truck to a 32 ft rooftop. A block and tackle system with 50 lb of effort force is designed to lift the materials.
14.What is the required actual mechanical advantage?
FormulaSubstitute / SolveFinal Answer
15.How many supporting strands will be needed in the pulley system? FormulaSubstitute / SolveFinal Answer
A block and tackle system with nine supporting strands is used to lift a metal lathe in a manufacturing facility. The motor being used to wind the cable in the pulley system can provide 100 lb of force.
16.What is the mechanical advantage of the system?
FormulaSubstitute / SolveFinal Answer
17.What is the maximum weight of the lathe?
FormulaSubstitute / SolveFinal Answer
Simple Machines – Inclined Plane
A civil engineer...
You May Also Find These Documents Helpful
Essay about Simple Machines
HanicalSimple Machines and its Mechanical Advantage What are Simple Machines ? What do we mean by Mechanical Advantage? Simple Machines * creates a greater output force than the input force Therefore since work is performed by applying a force over a distance, with the use of these machines we can do more work with lesser effort than working with our bare hands. In short, they make work easier. Mechanical Advantage * The Ratio between the input force and the output force. * The measure of the force amplification achieved by using a tool, mechanical device or machine system. Anyway what is input and output force? Input refers to the force you applied while output refers to the resultant force the object has from the input force. Example: I pushed a ball with 10 N of force, it is rolling with 10 N of force. I input 10 N into it, now it is outputting 10 N. The Six Classical Simple Machines The Lever(French word that means “to raise”) * A simple machine that allows you to gain a mechanical advantage in moving an object or in applying a force to an object. It is considered a "pure" simple machine because friction is not a factor to overcome, as in other simple machines . Part | Description | Fulcrum | Is where a solid board or rod can pivot...
Simple Machine Essay
...Simple Machine Joemarie A. Martinez 1-D CE Simple machine Simple machines make work easier by multiplying, reducing, or changing the direction of a force. The scientific formula for work is w = f x d, or, work is equal to force multiplied by distance. Simple machines cannot change the amount of work done, but they can reduce the effort force that is required to do the work! As you can see by this formula, if the effort force is reduced, distance is increased. These simple machines fall into two classes: (i) the inclined plane, wedge, screw characterized by the vector resolution of forces and movement along a line, and (ii) the lever, pulley, wheel and axle characterized by the equilibrium of torques and movement around a pivot. Wedges and screws are both a type of inclined plane; pulleys and wheels and axles are both a form of lever A simple machine is an elementary device that has a specific movement (often called a mechanism), which can be combined with other devices and movements to form a machine . Thus simple machines are considered to be the "building blocks" of more complicated machines . This analytical view of machines as decomposable into simple machines first arose in the Renaissance...
Simple Machines Essay
...Simple Machines Definitions: Machine - A device that makes work easier by changing the speed , direction, or amount of a force. Simple Machine - A device that performs work with only one movement. Simple machines include lever, wheel and axle, inclined plane, screw, and wedge. Ideal Mechanical Advantage (IMA)- A machine in which work in equals work out; such a machine would be frictionless and a 100% efficient IMA= De/Dr Actual Mechanical Advantage (AMA)- It is pretty much the opposite of IMA meaning it is not 100% efficient and it has friction. AMA= Fr/Fe Efficiency- The amount of work put into a machine compared to how much useful work is put out by the machine ; always between 0% and 100%. Friction- The force that resist motion between two surfaces that are touching each other. What do we use machines for? Machines are used for many things. Machines are used in everyday life just to make things easier. You use many machines in a day that you might take for granted. For example a simple ordinary broom is a machine . It is a form of a lever. Our country or world would never be this evolved if it wasn"t for machine . Almost every thing we do has a machine involved. We use machines ...
Simple Machine A machine with few Essay
... Simple Machine : A machine with few or no moving parts. Simple machines make work easier. Examples: Screw, Wheel and Axle, Wedge, Pulley, Inclined Plane, Lever Compound Machine : Two or more simple machines working together to make work easier. Examples: Wheelbarrow, Can Opener, Bicycle Inclined plane: A sloping surface, such as a ramp. Makes lifting heavy loads easier. The trade-off is that an object must be moved a longer distance than if it was lifted straight up, but less force is needed. Examples: Staircase, Ramp Lever: A straight rod or board that pivots on a point known as a fulcrum. Pushing down on one end of a lever results in the upward motion of the opposite end of the fulcrum. Examples: Door on Hinges, Seesaw, Hammer, Bottle Opener Pulley: A wheel that usually has a groove around the outside edge for a rope or belt. Pulling down on the rope can lift an object attached to the rope. Work is made easier because pulling down on the rope is made easier due to gravity. Examples: Flag Pole, Crane, Mini-Blinds Screw: An inclined plane wrapped around a shaft or cylinder. This inclined plane allows the screw to move itself or to move an object or material surrounding it when rotated. Examples: Bolt, Spiral Staircase Wedge: Two inclined planes joined back to back. Wedges are used to split things....
Simple Machines Examples With Pictures Essay
Applied Force Other First Class Lever Examples Applied Force Action Force Spring Load Force Action http://library.thinkquest.org/J002079F/lever.htm Third Class Lever Effort or Applied Force Egg ready to be launched Release hook Compressed Spring Load or Resistance Fulcrum Applied force can be in any direction http://www.usoe.k12.ut.us/curr/science/sciber00/8th/machines /sciber/lever3.htm http://www.usoe.k12.ut.us/curr/science/sciber00/8th/machines /images/tweezer.gif http://www.usoe.k12.ut.us/curr/science/sciber00/8th/machines /images/base.jpg Inclined Plane An inclined plane is a slanted surface used to raise an object. An inclined plane decreases the size of the effort force needed to move an object. However, the distance through which the effort force is applied is increased. The Big Rock rolling downhill with gravitational force IS NOT an example of an inclined plane. The inclined plane gives you mechanical advantage AGAINST gravity. Big Rock http://www.sirinet.net/~jgjohnso/simple.html An example of how an Inclined Plane can be used to raise a mass to activate another simple machine Egg ready to be launched By First Class Lever F Big Rock Force pushing (or pulling) Big Rock up the hill Inclined Plane First Class Lever Wedges Pulleys Wedges are moving inclined planes that are driven under loads to lift Pulleys use a wheel or set of wheels around which a single length (not...
Essay on Simple Machines
...Simple machines are extremely important to everyday life. They make stuff that is normally difficult a piece of cake. There are several types of simple machines . The first simple machine is a lever. A lever consists of a fulcrum, load, and effort force. A fulcrum is the support. The placing of the fulcrum changes the amount of force and distance it will take in order to move an object. The load is the applied force. The effort force is the force applied on the opposite side of the load. Levers can be placed in three classes. The 1st class levers are objects like pliers where the fulcrum is at the center of the lever. The 2nd class of levers are objects that have the fulcrum on the opposite side of the applied force like a nutcracker. The 3rd and final class is objects like crab claws. These objects of the load at one end and the fulcrum on the other. An inclined plane is another simple machine . Inclined planes are also known as ramps. Ramps make a trade off between distance and force. No matter how steep the ramp, the work is still the same. A winding road on a mountain side is a good example of a ramp. Some simple machines are modified inclined planes. The wedge is one of those machines . One or two inclined planes make up a wedge. Saws, knives,needles, and axes are made from wedges....
Practice Acl Problem Answers Essay
Chapter 7 ← Problem 7-43 - ACL Problem Solution a. There are 44 payroll transactions in the Payroll file. (This is determined by reading the number at the bottom of the screen.) b. The largest and smallest gross pay amounts for September are $4,395.83 and $1,278.33, respectively. (Use Quick Sort.) c. Total gross pay for September was $99,585.46. (Use the Total command.) d. The report on the following page shows gross pay by department. (Use the Summarize command on the Gross Pay column, save to a file, and print.) Note that this screenshot was produced using the “Screen” option in the Output tab of the Summarize window. Students’ hardcopy printouts will appear slightly different, but will contain the same departmental totals. e. There are no exceptions in the calculation of net pay for September. (Use the following Filter: Gross Pay – Taxes < > Net Pay.) f. There are no duplicate check numbers. (Use the Duplicates command on the check number column). There are four missing checks (#12389- #12392). The audit concern is that there may be unrecorded payroll transactions. (Use the Gaps command on the check number column.) Report for requirement d: Chapter 8 Problem 8-41 – ACL Problem Solution a. The following is a printout of the Statistics command for Inventory Value at Cost: Field: Value...
Simple Regression Model Practice Problems Essay
Chapter 4 Simple regression model Practice problems Use Chapter 4 Powerpoint question 4.1 to answer the following questions: 1. Report the Eveiw output for regression model . Please write down your fitted regression model. 2. Are the sign for consistent with your expectation, explain? 3. Hypothesize the sign of the coefficient and test your hypothesis at 5% significance level using t-table. 4. What percentage of variation in 30 year fixed mortgage rate is explained by this model? Why? Use Chapter 4 Powerpoint question 4.2 to answer the following questions: 5. Report the Eveiw output for regression model Based on the estimation period of 1986.01 – 1999.07. Please write down your fitted regression model. 6. Is Trend correlated with USPI? Set up the hypothesis testing at 5% significance level. 7. What percentage of variation in USPI is explained by this model? Why? 8. Based on your Eview model, report your forecast of USPI for the period of 1999.08-2000.07. Report RMSE. Use Chapter 4 Powerpoint question 4.3 to answer the following questions: 9. Report the Eveiw output for regression model USPIt = (USTBR)t + t based on the estimation period of 1986.01 – 1999.07. Please write down your fitted regression model. Dependent Variable: USPI | | | Method: Least Squares | | | Date: 01/24/11 Time: 16:46 | | | Sample:...