Заинтересуется topic simple machines. Методическая разработка занятия по английскому языку на тему "Машины и работа" (3 курс)

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Machines, simple

A simple machine is a device for doing work that has only one part. Simple machines redirect or change the size of forces, allowing people to do work with less muscle effort and greater speed, thus making their work easier. There are six kinds of simple machines: the lever, the pulley, the wheel and axle , the inclined plane , the wedge, and the screw.

Everyday work

We all do work in our daily lives and we all use simple machines every day. Work as defined by science is force acting upon an object in order to move it across a distance. So scientifically, whenever we push, pull, or cause something to move by using a force, we are performing work. A machine is basically a tool used to make this work easier, and a simple machine is among the simplest tools we can use. Therefore, from a scientific standpoint, we are doing work when we open a can of paint with a screwdriver, use a spade to pull out weeds, slide boxes down a ramp, or go up and down on a see-saw. In each of these examples we are using a simple machine that allows us to achieve our goal with less muscle effort or in a shorter amount of time.

Earliest simple machines

This idea of doing something in a better or easier way or of using less of our own muscle power has always been a goal of humans. Probably from the beginning of human history, anyone who ever had a job to do would eventually look for a way to do it better, quicker, and easier. Most people try to make a physical job easier rather than harder to do. In fact, one of our human predecessors is called Homo habilis, which means "handy man" or "capable man." This early version of our human ancestors was given that name because, although not quite fully human, it had a large enough brain to understand the idea of a tool, as well as hands with fingers and thumbs that were capable of making and using a tool. Therefore, the first simple machine was probably a strong stick (the lever) that our ancestor used to move a heavy object, or perhaps it was a sharp rock (the wedge) used to scrape an animal skin, or something else equally simple but effective. Other early examples might be a rolling log, which is a primitive form of the wheel and axle , and a sloping hill, which is a natural inclined plane . There is evidence throughout all early civilizations that humans used simple machines to satisfy their needs and to modify their environment.

Words to Know

Compound machine: A machine consisting of two or more simple machines.

Effort force: The force applied to a machine.

Fulcrum: The point or support on which a lever turns.

Resistance force: The force exerted by a machine.

Work: Transfer of energy by a force acting to move matter.

The beauty of simple machines is seen in the way they are used as extensions of our own muscles, as well as in how they can redirect or magnify the strength and force of an individual. They do this by increasing the efficiency of our work, as well as by what is called a mechanical advantage. A mechanical advantage occurs when a simple machine takes a small "input" force (our own muscle power) and increases the magnitude of the "output" force. A good example of this is when a person uses a small input force on a jack handle and produces an output force large enough to easily lift one end of an automobile. The efficiency and advantage produced by such a simple device can be amazing, and it was with such simple machines that the rock statues of Easter Island , the stone pillars of Stonehenge, and the Great Pyramids of Egypt were constructed. Some of the known accomplishments of these early users of simple machines are truly amazing. For example, we have evidence that the builders of the pyramids moved limestone blocks weighing between 2 and 70 tons (1.8 and 63.5 metric tons) hundreds of miles, and that they built ramps over 1 mile (1.6 kilometers) long.

Trade-offs of simple machines

One of the keys to understanding how a simple machine makes things easier is to realize that the amount of work a machine can do is equal to the force used, multiplied by the distance that the machine moves or lifts the object. In other words, we can multiply the force we are able to exert if we increase the distance. For example, the longer the inclined plane— which is basically a ramp— the smaller the force needed to move an object. Picture having to lift a heavy box straight up off the ground and place it on a high self. If the box is too heavy for us to pick up, we can build a ramp (an inclined plane) and push it up. Common sense tells us that the steeper (or shorter) the ramp, the harder it is to push the object to the top. Yet the longer (and less steep) it is, the easier it is to move the box, little by little. Therefore, if we are not in a hurry (like the pyramid builders), we can take our time and push it slowly up the long ramp to the top of the shelf.

Understanding this allows us also to understand that simple machines involve what is called a "trade-off." The trade-off, or the something that is given up in order to get something else, is the increase in distance. So although we have to use less force to move a heavy object up a ramp, we have increased the distance we have to move it (because a ramp is not the shortest distance between two points). Most primitive people were happy to make this trade-off since it often meant being able to move something that they otherwise could not have moved.

Today, most machines are complicated and use several different elements like ball bearings or gears to do their work. However, when we look at them closely and understand their parts, we usually see that despite their complexity they are basically just two or more simple machines working together. These are called compound machines. Although some people say that there are less than six simple machines (since a wedge can be considered an inclined plane that is moving, or a pulley is a lever that rotates around a fixed point), most authorities agree that there are in fact six types of simple machines.

Lever

A lever is a stiff bar or rod that rests on a support called a fulcrum (pronounced FULL-krum) and which lifts or moves something. This may be one of the earliest simple machines, because any large, strong stick would have worked as a lever. Pick up a stick, wedge it under one edge of a rock, and push down and you have used a lever. Downward motion on one end results in upward motion on the other. Anything that pries something loose is also a lever, such as a crow bar or the claw end of a hammer. There are three types or classes of levers. A first-class lever has the fulcrum or pivot point located near the middle of the tool and what it is moving (called the resistance force). A pair of scissors and a seesaw are good examples. A second-class lever has the resistance force located between the fulcrum and the end of the lever where the effort force is being made. Typical examples of this are a wheelbarrow, nutcracker, and a bottle opener. A third-class lever has the effort force being applied between the fulcrum and the resistance force. Tweezers, ice tongs, and shovels are good examples. When you use a shovel, you hold one end steady to act as a fulcrum, and you use your other hand to pull up on a load of dirt. The second hand is the effort force, and the dirt being picked up is

the resistance force. The effort applied by your second hand lies between the resistance force (dirt) and the fulcrum (your first hand).

Pulley

A pulley consists of a grooved wheel that turns freely in a frame called a block through which a rope runs. In some ways, it is a variation of a wheel and axle, but instead of rotating an axle, the wheel rotates a rope or cord. In its simplest form, a pulley"s grooved wheel is attached to some immovable object, like a ceiling or a beam. When a person pulls down on one end of the rope, an object at the opposite end is raised. A simple pulley gains nothing in force, speed, or distance. Instead, it only changes the direction of the force, as with a Venetian blind (up or down). Pulley systems can be movable and very complex, using two or more connected pulleys. This permits a heavy load to be lifted with less force, although over a longer distance.

Wheel and axle

The wheel and axle is actually a variation of the lever (since the center of the axle acts as the fulcrum). It may have been used as early as 3000 b.c., and like the lever, it is a very important simple machine. However, unlike the lever that can be rotated to pry an object loose or push a load along, a wheel and axle can move a load much farther. Since it consists of a large wheel rigidly attached to a small wheel (the axle or the shaft), when one part turns the other also does. Some examples of the wheel and axle are a door knob, a water wheel , an egg beater, and the wheels on a wagon, car, or bicycle. When force is applied to the wheel (thereby turning the axle), force is increased and distance and speed are decreased. When it is applied to the axle (turning the wheel), force is decreased and distance and speed are increased.

Inclined plane

An inclined plane is simply a sloping surface. It is used to make it easier to move a weight from a lower to a higher spot. It takes much less effort to push a wheel barrow load slowly up a gently sloping ramp than it does to pick it up and lift it to a higher spot. The trade-off is that the load must be moved a greater distance. Everyday examples are stairs, escalators, ladders, and a ship"s plank.

Wedge

A wedge is an inclined plane that moves and is used to increase force— either to separate something or to hold things together. With a wedge, the object or material remains in place while the wedge moves. A wedge can have a single sloping surface (like a door stop that holds a door tightly in place), or it can have two sloping surfaces or sides (like the wedge that splits a log in two). An axe or knife blade is a wedge, as is a chisel, plow, and even a nail.

Screw

A screw can be considered yet another form of an inclined plane, since it can be thought of as one that is wrapped in a spiral around a cylinder or post. In everyday life, screws are used to hold things together and to lift other things. When it is turned, a screw converts rotary (circular) motion into a forward or backward motion. Every screw has two parts: a body or post around which the inclined plane is twisted, and the thread (the spiraled inclined plane itself). Every screw has a thread, and if you look very closely at it, you will see that the threads form a tiny "ramp"

that runs from the tip to the top. Like nails, screws are used to hold things together, while a drill bit is used to make holes. Other examples of screws are airplane and boat propellers.

In physics, a simple machine is any device that requires the application of only one force in order to perform work. Work is the product of the force applied and the distance moved due to the force. Most authorities list six kinds of simple machines: levers, pulleys, wheels and axles, inclined planes, wedges, and screws. One can argue, however, that these six machines are not entirely different from each other. Pulleys and wheels and axles, for example, are really special kinds of levers, and wedges and screws are special kinds of inclined planes.

Levers

A lever is a simple machine that consists of a rigid bar supported at one point, known as the fulcrum. A force called the effort force is applied at one point on the lever in order to move an object, known as the resistance force, located at some other point on the lever. A common example of the lever is the crow bar used to move a heavy object such as a rock. To use the crow bar, one end is placed under the bar, which is supported at some point (the fulcrum) close to the rock. A person then applies a force at the opposite end of the crow bar to lift the rock. A lever of the type described here is a first-class lever because the fulcrum is placed between the applied force (the effort force) and the object to be moved (the resistance force).

The effectiveness of the lever as a machine depends on two factors: the forces applied at each end and the distance of each force from the fulcrum. The farther a person stands from the fulcrum, the more his or her force on the lever is magnified. Suppose that the rock to be lifted is only one foot from the fulcrum and the person trying to lift the rock stands 2 yd (1.8 m) from the fulcrum. Then, the person’ s force is magnified by a factor of six. If he or she pushes down with a force of 30 lb (13.5 kg), the object that is lifted can be as heavy as 180 (6 x 30) lb (81 kg).

Two other types of levers exist. In one, called a second-class lever, the resistance force lies between the

effort force and the fulcrum. A nutcracker is an example of a second-class lever. The fulcrum in the nutcracker is at one end, where the two metal rods of the device are hinged together. The effort force is applied at the opposite ends of the rods, and the resistance force, the nut to be cracked open, lies in the middle.

In a third-class lever, the effort force lies between the resistance force and the fulcrum. Some kinds of garden tools are examples of third-class levers. When a person uses a shovel, for example, one holds the handle end steady to act as the fulcrum, while using the other hand to pull up on a load of dirt. The second hand is the effort force, and the dirt being picked up is the resistance force. The effort applied by the second hand lies between the resistance force (the dirt) and the fulcrum (the first hand).

Mechanical advantage

The term mechanical advantage is used to described how effectively a simple machine works. Mechanical advantage is defined as the resistance force moved divided by the effort force used. In the lever example above, for example, a person pushing with a force of 30 lb (13.5 kg) was able to move an object that weighed 180 lb (81 kg). So, the mechanical advantage of the lever in that example was 180 lb divided by 30 lb, or 6.

The mechanical advantage described here is really the theoretical mechanical advantage of a machine. In actual practice, the mechanical advantage is always less than what a person might calculate. The main reason for this difference is resistance. When a person does work with a machine, there is always some resistance to that work. For example, a mathematician can calculate the theoretical mechanical advantage of a screw (a kind of simple machine) that is being forced into a piece of wood by a screwdriver. The actual mechanical advantage is much less than what is calculated because friction must be overcome in driving the screw into the wood.

Sometimes the mechanical advantage of a machine is less than one. That is, a person has to put in more force than the machine can move. Class three levers are examples of such machines. A person exerts more force on a class three lever than the lever can move. The purpose of a class three lever, therefore, is not to magnify the amount of force that can be moved, but to magnify the distance the force is being moved.

As an example of this kind of lever, imagine a person who is fishing with a long fishing rod. The person will exert a much larger force to take a fish out of the water than the fish itself weighs. The advantage of the fishing pole, however, is that it moves the fish a large distance, from the water to the boat or the shore.

Pulleys

A pulley is a simple machine consisting of a grooved wheel through which a rope runs. The pulley can be thought of as a kind of lever if one thinks of the grooved wheel as the fulcrum of the lever. Then the effort force is the force applied on one end of the pulley rope, and the resistance force is the weight that is lifted at the opposite end of the pulley rope.

In the simplest form of a pulley, the grooved wheel is attached to some immovable object, such as a ceiling or beam. When a person pulls down on one end of the pulley rope, an object at the opposite end of the rope is raised. In a fixed pulley of this design, the mechanical advantage is one. That is, a person can lift a weight equal to the force applied. The advantage of the pulley is one of direction. An object can be made to move upward or downward with such a pulley. Venetian blinds are a simple example of the fixed pulley.

In a movable pulley, one end of the pulley rope is attached to a stationary object (such as a ceiling or beam), and the grooved wheel is free to move along the rope. When a person lifts on the free end of the rope, the grooved wheel and any attached weight slides upward on the rope. The mechanical advantage of this kind of pulley is two. That is, a person can lift twice as much weight as the force applied on the free end of the pulley rope.

More complex pulley systems can also be designed. For example, one grooved wheel can be attached to a stationary object, and a second movable pulley can be attached to the pulley rope. When a person pulls on the free end of the pulley rope, a weight attached to the movable pulley can be moved upward with a mechanical advantage of two. In general, in more complicated pulley systems, the mechanical advantage of the pulley is equal to the number of ropes that hold up the weight to be lifted. Combinations of fixed and movable pulleys are also known as a block and tackle . Some blocks and tackles have mechanical advantages high enough to allow a single person to lift weights as heavy as that of an automobile.

Wheel and axle

A second variation of the lever is the simple machine known as a wheel and axle . A wheel and axle consists of two circular pieces of different sizes attached to each other. The larger circular piece is the wheel in the system, and the smaller circular piece is the axle. One of the circular pieces can be considered as the effort arm of the lever and the second, the resistance arm. The place at which the two pieces is joined is the fulcrum of the system.

Some examples of the wheel and axle include a door knob, a screwdriver, an egg beater, a water wheel , the steering wheel of an automobile, and the crank used to raise a bucket of water from a well. When the wheel in a wheel and axle machine is turned, so is the axle, and vice versa. For example, when someone turn the handle of a screwdriver, the edge that fits into the screw head turns at the same time.

The mechanical advantage of a wheel and axle machine can be found by dividing the radius of the wheel by the radius of the axle. For example, suppose that the crank on a water well turns through a radius of 2 ft (61 cm) and the radius of the axle around which the rope is wrapped is 4 in (10 cm). Then, the mechanical advantage of this wheel and axle system is 2 ft divided by 4 in, or 6.

Inclined planes

KEY TERMS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Compound machine

A machine consisting of two or more simple machines.

Effort force

The force applied to a machine.

Friction

A force caused by the movement of an object through liquid, gas, or against a second object that works to oppose the first object"s movement.

Mechanical advantage

A mathematical measure of the amount by which a machine magnifies the force put into the machine.

Resistance force

The force exerted by a machine.

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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. The screw is another modified inclined plane. Screws decrease the force but increase the distance. The ridges are called threads. A couple of simple machines are made with wheels. The wheel and axle is one of these machines.

These are made with a rod joined to the center of a wheel. They can either increase distance or force, depending on the size of the wheel. The pulley is another machine that uses wheels. The are a wheel with a groove in the center with a rope or chain stretched around it. The load attaches to one end and the effort is applied to the other on all pulleys. There are two types of pulleys. The fixed pulley stays in one place while the wheel spins. Movable pulleys attach to objects. Several pulleys can be used at one time. A good example of a pulley system is an escalator. Simple machines make up compound machines. We use these machines daily. Life would be difficult without simple machines.

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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...

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...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....

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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:...

Simple Machines Examples With Pictures Essay

Activity 1.1.2 Simple Machines Practice Problems Answer Key Essay

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? Formula Substitute / Solve Final Answer AMA = 3.33 3. Using static equilibrium calculations, calculate the length from the fulcrum to the resistance force. Formula Substitute / Solve Final 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?...

Compound Machine

Our compound machine , consisting of mainly three different simple machines , is a crane designed to multiply your force in order to effectively and efficiently lift the four 75 kg up a steep hill. Our machine starts off with the gear train. As you rotate the handle, all the gears rotate along as well. Since we connected the rope of the pulley to our gears, it then puts the pulley system into action. We created movable pulleys throughout the arm until the tip to stabilize our rope and also give us a mechanical advantage. At the top section of our arm we created a lever to support the load. This magnifies our effort force since a combination of all the mechanical energy is being carried out. With the pulley system, connected all the way to the gear train, and the lever working all together, our mechanical advantage is increased greatly. We created a series of gear trains to not only increase our advantage of torque in the machine but also to increase the mechanical advantage rather than losing efficiency due to friction and thermal energy. Doing this, we magnified our effort force onto the load. Also, in the gears, we arranged it so that the input gear and the output gear gave us a low gear ratio and the idler gears in between. It also allows us to control the direction of our force in the machine . Since it is linked to the pulley, we can control the direction of the rope. However, it only...

Essay

SAMPLE PROBLEMS: . 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. Sketch and annotate the lever system described above. | What is the actual mechanical advantage of the system? Formula | Substitute / Solve | Final Answer | | | AMA = 3.33 | * Using static equilibrium calculations, calculate the length from the fulcrum to the resistance force. Formula | Substitute / Solve | Final 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. Illustrate and annotate the lever system described above. | What is the ideal mechanical advantage of the system? Formula | Substitute / Solve | Final Answer | | | | * Using static equilibrium calculations, calculate the effort force needed to overcome the resistance force in the system. Formula | Substitute / Solve | Final 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. Sketch and annotate the lever system...

Essay on Simple Machines

Simple Machines Essay

Simple Machine A machine with few Essay

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 .