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Machines A machine is a device that changes the force or increases the motion from work. Some machines, such as knives, scissors, and doorknobs make doing work easier. Some machines, such as bicycles, increase speed. Some machines, such as an axe, change the direction of force. Some machines, such as a car jack, increase force. Work and Machines Copyright © McGraw-Hill Education
Types of Simple Machines A simple machine is a machine that does work with only one movement of the machine. There are six types of simple machines: lever pulley wheel and axle inclined plane screw wedge Work and Machines Copyright © McGraw-Hill Education
Compound Machines A compound machine is a combination of two or more simple machines. A pair of scissors is a compound machine that combines two wedges and two levers. A bicycle is also a compound machine made up of two wheel and axle systems. Work and Machines Copyright © McGraw-Hill Education
Calculating Efficiency Efficiency is a measure of how much of the work put into a machine is changed into useful output work by the machine. Every machine is less than 100% efficient. Work and Machines Copyright © McGraw-Hill Education
Work and Machines Copyright © McGraw-Hill Education SOLVE FOR EFFICIENCY EVALUATE THE ANSWER The work out is about half of the work in. Therefore, an answer close to 50 percent is reasonable. Use with Example Problem 2. Problem You do 20 J of work in pushing a crate up a ramp. If the output work from the inclined plane is 11 J, then what is the efficiency of the inclined plane? Response ANALYZE THE PROBLEM KNOWN work in: W in = 20 J work out: W out = 11 J UNKNOWN efficiency: e
Mechanical Advantage The ratio of the output force to the input force is the mechanical advantage of a machine. Two forces are involved when a machine is used to do work. The force that is applied to the machine is called the input force. F in stands for the effort force. The force applied by the machine is called the output force, symbolized by F out. Work and Machines Copyright © McGraw-Hill Education
Mechanical Advantage Window blinds are a machine that changes the direction of an input force. A downward pull on the cord is changed to an upward force on the blinds. The input and output forces are equal, so the MA is 1. Work and Machines Copyright © McGraw-Hill Education
Describing Energy Copyright © McGraw-Hill Education SOLVE FOR MECHANICAL ADVANTAGE EVALUATE THE ANSWER The weight of the crate is very close to four times the force needed to lift the crate. Therefore, the mechanical advantage of the crate should be close to 4. Our answer is close to 4, so it is reasonable. Use with Example Problem 3. Problem A crate weighs 950 N. If you can use a pulley system to lift that crate with a force of only 250 N, then what is the mechanical advantage of the pulley system? Response ANALYZE THE PROBLEM KNOWN output force: F out = 950 N input force: F in = 250 N UNKNOWN mechanical advantage: MA
Machines make doing work easier or faster by changing the force needed to do the work. Section 1: Work and Machines K What I Know W What I Want to Find.
4.1 Essential Questions What is work? How can work be calculated when force and motion are parallel to each other? How do machines make doing work easier?
Mechanical Advantage The measurement of how useful a machine is to the job.
Simple Machines Machines Lever Inclined plane Pulley Screw Wedge Wheel & axle.
CP Physics Ms. Morrison MACHINE NOTES. MACHINES Devices that make work easier to do (transfer energy) Two ways make work easier: Machines change the direction.
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What is a Machine? Definition: any device that makes work easier by changing a force Work is done whenever a force moves an object over a distance.
Section 2Work and Energy EQ: How are work and mechanical advantage of simple machines calculated?
Machines and Mechanical Advantage Archimedes (Greek mathematician, 287 to 212 B.C.) said, “Give me a place to stand and I will move the Earth,” meaning.
Work & Power How the world works….. Define / Describe WORK Work is done when a force causes an object to move in the direction that the force is applied.
6 Simple Machines 1st CLASS 2nd CLASS 3rd CLASS Inclined Plane.
What is a machine? A machine is a device that makes doing work easier. Machines can be simple. Some, like knives, scissors, and doorknobs, are used everyday.
What is a simple machine? Section 5-1. Machines Makes work easier by changing the size of a force, the direction of a force, or the speed of a force.
Chapter 11 work and machines. Anytime that you exert a force and cause an object to move in the direction of the applied force you do _________. work.
REVIEW Work Power and Machines. What Is Work? Key Concepts Work is done on an object when the object moves in the same direction in which the force.
Classification of simple machines: Simple machines are divided into two families: 1)The Lever family and 2) The inclined plane family The Lever family.
Work, Machines, and Energy. Work and Power Work is done if (1) an object moves, and (2) if a force acts in the same direction that the object moves.
Title (Your Names). Work What is work? Formula for work Examples.
OBJECTIVES 05-1 Explain the meaning of work. Describe how work and energy are related. Calculate work. Calculate power.
Work and Machines Work is a form of energy. It is the energy that it takes to cause things to move. Sometimes called Mechanical Energy. The Formula.
Section 2Work and Energy What Are Simple Machines? 〉 What are the six types of simple machines? 〉 The six types of simple machines are the simple lever,
Pay attention. Simple Machines Simple machines assist us in doing work by creating a mechanical advantage. They do not change the amount of work; they.
Physical Chapter Seven Simple Machines Levers Pulleys Inclined Planes Screws Wheel & Axle Wedge Compound Machines.
+ Do Now Why do we use ramps to move heavy objects to higher places?
Work, Power and Machines. Work Work- quantity of force applied over a distance. Is done when force causes motion of an object. Work equation: work =
Science 8: Unit D: Mechanical Systems Topic 1: Levers and Inclined Planes.
Simple Machines. A Simple Machine is a machine with few or no moving parts. Simple machines make work easier.
Machines, Machines, Machines. When a force moves an object in the direction you are pushing or pulling that object Work.
Ch 9 What is Work ? What is the equation for work? Work is done only when force cause a change in the motion of an object. Is this a good example of Work?
Work and Machines. What is Work? Work is force times distance. To be exact, work is force times the distance moved in the direction of the force. The.
Work, Power, and Machines Glencoe Chapter 5. A. Work is the transfer of energy that occurs when a force makes an object move. 1. For work to occur, an.
Work What kind of work do you do?. Work Scientists say work is… –force applied through a distance Think of it this way, –Are you doing homework if you.
Machines Making Work Easier. What Is A Machine? A machine is a device that makes work easier Examples 1. Doorknob 2. Pencil Sharpener 3. Knife 4. Crow.
S8P3. Students will investigate relationship between force, mass, and the motion of objects. c. Demonstrate the effect of simple machines (lever, inclined.
Physical Science Chapter 14 Review Game. Work and Power EfficiencyMachines Mechanical Advantage 1 point 1 point 1 point 1 point 1 point 1 point 1 point.
Section 2Work and Energy Simple Machines Chapter 13.2.
CHAPTER THREE : WORK AND SIMPLE MACHINES. Lesson 1: Work and Power What is work? Work is the transfer of energy to an object by a force that makes.
A machine is a device that makes doing work easier. Machines can be simple. Some, like knives, scissors, and doorknobs, are used everyday to make.
The transfer of energy to an object by the application of a force that causes the object to move in the direction of the force. work.
Simple Machines W O R K M e c h a n i c a l A d v a n t a g e Force Effort E f f i c i e n c y 1.
Warm Up: 1/14/13 Give an example of a machine you use on a daily basis. Then say how you thinks it helps to make work easier.
CHAPTER THREE : WORK AND SIMPLE MACHINES. Lesson 1: Work and Power What is work? Work is the transfer of ________to an object by a force that makes.
Name ________________________________Physical Science Date _______________Period ________Mrs. Haentges Notes for Chapter 6 – Work and Machines Work - _____energy.
Lesson 3: How are work and Motion related?. Work – the result of a force MOVING an object.
“Work and Energy” Chapter 13. Work Work is the quantity that measures the effects of a force acting over a distance. Work is the quantity that measures.
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