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

The

An inclined plane consists of a sloping surface; it is used for raising heavy bodies. The plane offers a in that the force required to move an object up the incline is less than the being raised (discounting ). The steeper the slope, or incline, the more nearly the required force approaches the actual weight. Expressed mathematically, the force F required to move a block D up an inclined plane without friction is equal to its weight W times the sine of the angle the inclined plane makes with the horizontal (θ). The equation is F = W sin θ.

The principle of the inclined plane is used widely-for example, in ramps and switchback roads, where a small force acting for a distance along a slope can do a large amount of work.

The

A lever is a bar or board that rests on a support called a fulcrum. A downward force exerted on one end of the lever can be transferred and increased in an upward direction at the other end, allowing a small force to lift a heavy weight.

All early people used the lever in some form, for example, for moving heavy stones or as digging sticks for land cultivation. The principle of the lever was used in the swape, or , a long lever pivoted near one end with a platform or water container hanging from the short arm and counterweights attached to the long arm. A man could lift several times his own weight by pulling down on the long arm. This device is said to have been used in Egypt and India for raising water and lifting soldiers over battlements as early as 1500 bce .

The

A wedge is an object that tapers to a thin edge. Pushing the wedge in one direction creates a force in a sideways direction. It is usually made of metal or wood and is used for splitting, lifting, or tightening, as in securing a hammer head onto its handle.

The wedge was used in prehistoric times to split logs and rocks; an is also a wedge, as are the teeth on a saw. In terms of its mechanical function, the screw may be thought of as a wedge wrapped around a cylinder.

The

A wheel and axle is made up of a circular frame (the wheel) that revolves on a shaft or rod (the axle). In its earliest form it was probably used for raising weights or water buckets from wells.

Its principle of operation is best explained by way of a device with a large and a small gear attached to the same shaft. The tendency of a force, F , applied at the radius R on the large gear to turn the shaft is sufficient to overcome the larger force W at the radius r on the small gear. The force amplification, or , is equal to the ratio of the two forces (W :F ) and also equal to the ratio of the radii of the two gears (R :r ).

If the large and small gears are replaced with large- and small-diameter drums that are wrapped with ropes, the wheel and axle becomes capable of raising weights. The weight being lifted is attached to the rope on the small drum, and the operator pulls the rope on the large drum. In this arrangement the mechanical advantage is the radius of the large drum divided by the radius of the small drum. An increase in the mechanical advantage can be obtained by using a small drum with two radii, r 1 and r 2 , and a pulley block. When a force is applied to the large drum, the rope on the small drum winds onto D and off of d.

A measure of the force amplification available with the pulley-and-rope system is the velocity ratio, or the ratio of the at which the force is applied to the rope (V F ) to the velocity at which the weight is raised (V W ). This ratio is equal to twice the radius of the large drum divided by the difference in the radii of the smaller drums D and d. Expressed mathematically, the equation is V F /V W = 2R /(r 2 - r 1). The actual mechanical advantage W /F is less than this velocity ratio, depending on friction. A very large mechanical advantage may be obtained with this arrangement by making the two smaller drums D and d of nearly equal radius.

What do a bicycle and a car have in common? They both move using the simple machine wheel and axle. In this lesson, students learn about how this simple machine works, and will identify objects that use a wheel and axle.

Materials and preparation

Related books and/or media

Key terms

• simple machine
• wheel

Learning Objectives

Students will be able to explain how the wheel and axle work as a simple machine. Students will be able to identify objects which use the wheel and axle.

Explicit Instruction/Teacher modeling

• 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

• 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

• 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

• Collect the worksheets that the students have filled out, and correct them using the Wheel and Axle answer sheet.

Review and closing

• 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.

Topic: Simple Machines PSSA: 3.4.7.C / S8.C.3.1

Objective: TLW compare different types of simple machines. TLW compare different types of simple machines. TLW explain the difference between a simple machine and a compound machine. TLW explain the difference between a simple machine and a compound machine.

MI #1: Levers A lever is a simple machine that has a bar that pivots on a fixed point called a fulcrum. A lever is a simple machine that has a bar that pivots on a fixed point called a fulcrum. Levers are classified based on the location of the input force, load, and the fulcrum. Levers are classified based on the location of the input force, load, and the fulcrum.

MI #2: Classes of Levers First class levers have the fulcrum between the input force and the load. First class levers have the fulcrum between the input force and the load. - Includes see-saws Second class levers have the load between the input force and the fulcrum. Second class levers have the load between the input force and the fulcrum. - Includes wheelbarrows Third class levers have the input force between the load and the fulcrum. Third class levers have the input force between the load and the fulcrum. - Includes hammers and fishing poles

Mi #3: Pulleys A pulley is a simple machine that has a grooved wheel that holds a rope or a chain. A pulley is a simple machine that has a grooved wheel that holds a rope or a chain. There are three types of pulleys; fixed, movable, and block and tackle. There are three types of pulleys; fixed, movable, and block and tackle.

MI #4: Wheel and Axle A wheel and axle consists of two circular objects of different sizes that rotate on the same axis. A wheel and axle consists of two circular objects of different sizes that rotate on the same axis. The axle rotates a smaller distance than the wheel, which results in a greater output force. The axle rotates a smaller distance than the wheel, which results in a greater output force.

MI #5: Inclined Planes An inclined plane is a straight slanted surface. An inclined plane is a straight slanted surface. A wedge is a pair of inclined planes that move. A wedge is a pair of inclined planes that move. A screw is an inclined plane wrapped around a cylinder. A screw is an inclined plane wrapped around a cylinder.

MI #6: Compound Machines A compound machine is a machine that is made of two or more simple machines working together. A compound machine is a machine that is made of two or more simple machines working together. Because compound machines have more moving parts, their mechanical efficiency is typically low. Because compound machines have more moving parts, their mechanical efficiency is typically low.

So What…? Real Life Application Machines make work easier, so it is important to understand the different types of simple machines. Machines make work easier, so it is important to understand the different types of simple machines.

Engineering Connection

Why do engineers care about simple machines? How do such devices help engineers improve society? Simple machines are important and common in our world today in the form of everyday devices (crowbars, wheelbarrows, highway ramps, etc.) that individuals, and especially engineers, use on a daily basis. The same physical principles and mechanical advantages of simple machines used by ancient engineers to build pyramids are employed by today"s engineers to construct modern structures such as houses, bridges and skyscrapers. Simple machines give engineers added tools for solving everyday challenges.

Learning Objectives

After this lesson, students should be able to:

• Understand what a simple machine is and how it would help an engineer to build something.
• Identify six types of simple machines.
• Understand how the same physical principles used by engineers today to build skyscrapers were employed in ancient times by engineers to build pyramids.
• Generate and compare multiple possible solutions to creating a simple lever machine based on how well each met the constraints of the challenge.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN) , a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g. , by state; within source by type; e.g. , science or mathematics; within type by subtype, then by grade, etc .

NGSS: Next Generation Science Standards - Science

International Technology and Engineering Educators Association - Technology

Lesson Closure

Today, we have discussed six simple machines. Who can name them for me? (Answer: Wedge, wheel and axle, lever, inclined plane, screw, and pulley.) How do simple machines make work easier? (Answer: Mechanical advantage enables us to use less force to move an object, but we have to move it a longer distance.) Why do engineers use simple machines? (Possible answers: Engineers creatively use their knowledge of science and math to make our lives better, often using simple machines. They invent tools that make work easier. They accomplish huge tasks that could not be done without the mechanical advantage of simple machines. They design structures and tools to use our environmental resources better and more efficiently.) Tonight, at home, think about everyday examples of the six simple machines. See how many you can find around your house!

Complete the KWL Assessment Chart (see the Assessment section). Gauge students" understanding of the lesson by assigning the Simple Machines Worksheet as a take-home quiz. As an extension, use the attached to conduct a simple machines scavenger hunt in which students find examples of simple machines used in the classroom and at home.

In other lessons of this unit, students study each simple machine in more detail and see how each could be used as a tool to build a pyramid or a modern building.

Vocabulary/Definitions

Design: (verb) To plan out in systematic, often graphic form. To create for a particular purpose or effect. Design a building. (noun) A well thought-out plan.

Engineering: Applying scientific and mathematical principles to practical ends such as the design, manufacture and operation of efficient and economical structures, machines, processes and systems.

Force: A push or pull on an object.

Inclined plane: A simple machine that raises an object to greater height. Usually a straight slanted surface and no moving parts, such as a ramp, sloping road or stairs.

Lever: A simple machine that increases or decreases the force to lift something. Usually a bar pivoted on a fixed point (fulcrum) to which force is applied to do work.

Mechanical advantage: An advantage gained by using simple machines to accomplish work with less effort. Making the task easier (which means it requires less force), but may require more time or room to work (more distance, rope, etc.). For example, applying a smaller force over a longer distance to achieve the same effect as applying a large force over a small distance. The ratio of the output force exerted by a machine to the input force applied to it.

Pulley: A simple machine that changes the direction of a force, often to lift a load. Usually consists of a grooved wheel in which a pulled rope or chain runs.

Pyramid: A massive structure of ancient Egypt and Mesoamerica used for a crypt or tomb. The typical shape is a square or rectangular base at the ground with sides (faces) in the form of four triangles that meet in a point at the top. Mesoamerican temples have stepped sides and a flat top surmounted by chambers.

Screw: A simple machine that lifts or holds materials together. Often a cylindrical rod incised with a spiral thread.

Simple machine: A machine with few or no moving parts that is used to make work easier (provides a mechanical advantage). For example, a wedge, wheel and axle, lever, inclined plane, screw, or pulley.

Spiral: A curve that winds around a fixed center point (or axis) at a continuously increasing or decreasing distance from that point.

Tool: A device used to do work.

Wedge: A simple machine that forces materials apart. Used for splitting, tightening, securing or levering. It is thick at one end and tapered to a thin edge at the other.

Wheel and axle: A simple machine that reduces the friction of moving by rolling. A wheel is a disk designed to turn around an axle passed through the center of the wheel. An axle is a supporting cylinder on which a wheel or a set of wheels revolves.

Work: Force on an object multiplied by the distance it moves. W = F x d (force multiplied by distance).

Assessment

Pre-Lesson Assessment

Know / Want to Know / Learn (KWL) Chart: Create a classroom KWL chart to help organize learning about a new topic. On a large sheet of paper or on the classroom board, draw a chart with the title "Building with Simple Machines." Draw three columns titled, K, W and L, representing what students know about simple machines, what they want to know about simple machines and what they learned about simple machines. Fill out the K and W sections during the lesson introduction as facts and questions emerge. Fill out the L section at the end of the lesson.

Post-Introduction Assessment

Reference Sheet: Hand out the attached Simple Machines Reference Sheet . Review the information and answer any questions. Suggest the students keep the sheet handy in their desks, folders or journals.

Lesson Summary Assessment

Closing Discussion: Conduct an informal class discussion, asking the students what they learned from the activities. Ask the students:

• Who can name the different types of simple machines? (Answer: Wedge, wheel and axle, lever, inclined plane, screw, and pulley.)
• How do simple machines make work easier? (Answer: Mechanical advantage enables us to use less force to move an object, but we have to move it a longer distance.)
• Why do engineers use simple machines? (Possible answers: Engineers creatively use their knowledge of science and math to make our lives better, often using simple machines. They invent tools that make work easier. They accomplish huge tasks that could not be done without the mechanical advantage of simple machines. They design structures and tools to use our environmental resources better and more efficiently.)

Remind students that engineers consider many factors when they plan, design and create something. Ask the students:

• What are the considerations an engineer must keep in mind when designing a new structure? (Possible answers: Size and shape (design) of the structure, available construction materials, calculation of materials needed, comparing materials and costs, making drawings, etc.)
• What are the considerations an engineer must keep in mind when choosing a site to build a new structure? (Possible answers: Site physical characteristics , distance to construction resources , suitability for the structure"s purpose .)

KWL Chart (Conclusion): As a class, finish column L of the KWL Chart as described in the Pre-Lesson Assessment section. List all of the things they learned about simple machines. Were all of the W questions answered? What new things did they learn?

Take-Home Quiz: Gauge students" understanding of the lesson by assigning the Simple Machines Worksheet as a take-home quiz.

Lesson Extension Activities

Use the attached Simple Machines Scavenger Hunt! Worksheet to conduct a fun scavenger hunt. Have the students find examples of all the simple machines used in the classroom and their homes.

Bring in everyday examples of simple machines and demonstrate how they work.

Illustrate the power of simple machines by asking students to do a task without using a simple machine, and then with one. For example, create a lever demonstration by hammering a nail into a piece of wood. Have students try to pull the nail out, first using only their hands

Bring in a variety of everyday examples of simple machines. Hand out one out to each student and have them think about what type of simple machine it is. Next, have students place the items into categories by simple machines and explain why they chose to place their item there. Ask students what life would be like without this item. Emphasize that simple machines make our life easier.

See the Edheads website for an interactive game on simple machines: http://edheads.org.

Engineering Design Fun with Levers: Give each pair of students a paint stirrer, 3 small plastic cups, a piece of duct tape and a wooden block or spool (or anything similar). Challenge the students to design a simple machine lever that will throw a ping pong ball (or any other type of small ball) as high as possible. In the re-design phase, allow the students to request materials to add on to their design. Have a small competition to see which group was able to send the ping pong ball flying high. Discuss with the class why that particular design was successful versus other variations seen during the competition.

Additional Multimedia Support

See http://edheads.org for a good simple machines website with curricular materials including educational games and activities.

References

Dictionary.com. Lexico Publishing Group, LLC. Accessed January 11, 2006. (Source of some vocabulary definitions, with some adaptation) http://www.dictionary.com

Simple Machines. inQuiry Almanack, The Franklin Institute Online, Unisys and Drexel eLearning. Accessed January 11, 2006. http://sln.fi.edu/qa97/spotlight3/spotlight3.html

Contributors

Copyright

Supporting Program

Acknowledgements

The contents of these digital library curricula were developed by the Integrated Teaching and Learning Program under National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the National Science Foundation, and you should not assume endorsement by the federal government. 

Last modified: December 4, 2019

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.

Cite this page

Simple Machines. (2016, Dec 12). Retrieved from ">APA "Simple Machines." StudyMoose , 12 Dec 2016, ">MLA StudyMoose. (2016). Simple Machines . . Available at: ">Harvard "Simple Machines." StudyMoose, Dec 12, 2016. Accessed January 17, 2020.