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Simple and Compound Machine bjkkkkkkk.pptx

Engineering

Engineering◦
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Simple & compound Machines
objectives • apply concepts of translational and rotational motion to design and build prototypes of efficient simple and compound machines; • explain the characteristics of efficient simple and compound machines;
What is a Machine? • A machine is a device that helps make work easier by changing the direction or magnitude of a force. • Classified as simple and compound machine.
What are Simple Machines? A simple machine is a tool that helps us do work more easily. It helps us lift, push, or pull things using less effort.
MECHANICAL ADVANTAGE Is the reduction of force needed.
Pulley • A simple machine made of a wheel with a groove around its edge, and a rope or cable that fits into the groove. • Pulleys are used to lift or move heavy objects more easily by changing the direction of the force you apply or by reducing the amount of force needed
A fixed pulley is attached to a support (like a ceiling). It lets you pull down to lift an object up, but you use the same amount of force as lifting the object directly. It only changes the direction of the force A movable pulley is attached to the object being lifted. It actually reduces the amount of force needed to lift the object, usually by half, because the weight is shared between two sections of the rope A compound pulley (or block and tackle) combines fixed and movable pulleys. This setup can reduce the force needed even more, making it possible to lift very heavy loads with much less effort
Wheel & Axle • A wheel and axle is a simple machine that helps us do work more easily by making it easier to move or lift things. • It consists of a large wheel attached to a smaller cylinder called the axle. • When you turn the wheel, the axle turns too.
How does a Wheel & Axle help us? A wheel and axle helps us by making it easier to carry heavy loads quickly over long distances. They can also help us steer, turn and lift loads. A wheelchair helps people move their bodies from one place to another.
Lever • It’s a rigid bar that can rotate around a fixed point called the fulcrum. • You apply force on one end (called the effort) to move a load (the resistance) on the other end. • Levers helps us by making it easier to lift heavy objects.
How does a lever help us? • First-class lever: The fulcrum is between the effort and the load. Ex. A seesaw or a crowbar. • Second-class lever: The load is between the fulcrum and the effort. Ex. A wheelbarrow. • Third-class lever: The effort is between the fulcrum and the load. Ex. Tweezers or a fishing rod.
Wedge • A wedge is made of two inclined planes joined back-to-back. It is used to split, cut, or push objects apart. • It makes work easier by spreading the force over a larger area and pushing materials apart. • The sharper and longer the wedge, the easier it is to cut or split something with less force.
Wedges help us by making it easier to split or cut an object. Objects like forks, knives and even our teeth are wedges. How do Wedges help us?
Screw • A screw is essentially an inclined plane wrapped around a shaft. • Holds things together A car jack is an example of a screw-type simple machine that enables one person to lift up the side of a car.
How do Screws help us? Screws help us by lifting things or keeping them together. A light bulb is screwed into the base so it does not fall out and lights up!
Inclined Plane An inclined plane is a flat, slanted surface used to move objects to a higher or lower place with less effort.
How do inclined PLanes help us? Inclined plane helps us by pushing or rolling an object to a higher or lower area. A slide is a fun and safe way to go from a higher area to a flat area.
Can you name all the Simple machines?
compound Machines
WHAT ARE COMPOUND MACHINES? A compound machine is a tool made up of two or more simple machines working together.
WHAT ARE COMPOUND MACHINES? • Car jack combines wedge and screw • Crane or tow truck combines lever and pulley • Wheelbarrow combines wheel and axle with a lever
summary
Questions: 1. What machines do you use regularly? 2. How does each machine help make work easier? 3. Where have you seen these machines applied in real-world engineering or construction?
Test 1. Multiple choice Write the letter of your answer.
GENERAL SCIENCE Simple and Compound Machines Multiple Choice Questions 1. What is the main purpose of a simple machine?** A) To increase the amount of work done B) To make work easier by changing the force or direction C) To reduce the distance over which work is done D) To increase the weight of an object 2. Which of the following is an example of a 1st class lever? A) Scissors B) Wheelbarrow C) Pulley D) Bicycle
GENERAL SCIENCE Simple and Compound Machines 3. A compound machine is made up of: A) Only one simple machine B) Machines that do not make work easier C) Two or more simple machines combined D) Machines that do not use any force 4. Which characteristic makes a machine efficient? A) It requires more force to do the work B) It reduces friction and effort needed C) It increases the distance to move the load D) It changes the color of the machine
5. What does mechanical advantage mean? A) The ratio of output force to input force B) The speed at which a machine moves C) The distance an object moves D) The weight of the machine 6. Which simple machine is a ramp an example of? A) Lever B) Pulley C) Inclined plane D) Wedge GENERAL SCIENCE Simple and Compound Machines
GENERAL SCIENCE Simple and Compound Machines 7. In a pulley system, adding more pulleys will: A) Decrease the force needed to lift the load B) Increase the force needed to lift the load C) Make the load heavier D) Have no effect on the force needed 8. Scissors are an example of a compound machine because they combine: A) Lever and wedge B) Pulley and wheel and axle C) Screw and inclined plane D) Wedge and screw
GENERAL SCIENCE Lesson 02- Characteristics of Efficient Simple and Compound Machines 9. Which of the following increases the efficiency of a machine? A) More friction C) More weight B) Less distance D) Less friction 10. Why do compound machines often make work easier than simple machines? A) They use more energy than simple machines B) They combine the advantages of several simple machines C) They are heavier than simple machines D) They require more force to finish a task
Test 2. Match the simple machine with its correct definition by writing the corresponding number in the answer column.
Test 3. Identify what example of simple machine is shown in each picture.
19-20. Describe what is a simple machine.
End of the test.