Monday, November 3Monday, November 3rdrd Entry TaskEntry Task

List the machines you used this List the machines you used this morning as you got ready for morning as you got ready for school.school.

Schedule:Schedule:• Intro to Chapter 14Intro to Chapter 14• 14.1 Machines help 14.1 Machines help

people do workpeople do work

Homework:Homework:• Finish vocabularyFinish vocabulary

Objective: Objective: •I will explain how I will explain how machines help people do machines help people do workwork

Please have on desk:Please have on desk:• Pencil, calculatorPencil, calculator

Machine PicturesMachine Pictures

Answer the following questions about Answer the following questions about each picture.each picture.

1.1.What is this machine designed to do?What is this machine designed to do?

2.2.Without a machine, how would humans Without a machine, how would humans do the job? do the job?

BackhoeBackhoe

CraneCrane

Table SawTable Saw

TruckTruck

Tuesday, November 4Tuesday, November 4thth Entry TaskEntry Task

Describe the two ways Describe the two ways that machines help that machines help people do work.people do work.

Schedule:Schedule:• Mechanical Advantage & Mechanical Advantage &

Efficiency MathEfficiency Math

Homework:Homework:• M A & Efficiency mathM A & Efficiency math

Objective: Objective: • I can calculate mechanical I can calculate mechanical advantage & efficiencyadvantage & efficiency

Please have on desk:Please have on desk:• Chapter 14 vocab and Chapter 14 vocab and

notesnotes

Machines can change forceMachines can change force

Machines can change Machines can change sizesize of force of force

Machines Help People Do WorkMachines Help People Do Work

Machines Help People Do WorkMachines Help People Do Work

Machines can change Machines can change distancedistance over which over which

force is appliedforce is applied

Machines Help People Do WorkMachines Help People Do Work

Machines can change Machines can change directiondirection of force of force

Mechanical AdvantageMechanical Advantage Machines give people an Machines give people an

advantageadvantage…they make work …they make work easiereasier

MA = MA = Output ForceOutput ForceInput ForceInput Force

If Output force is If Output force is largelarge and and Input force is Input force is smallsmall, the , the machine is better (Gives machine is better (Gives greater MA)greater MA)

Machines Help People Do WorkMachines Help People Do Work

Calculate MACalculate MA

Mr. Brownlee is trying to lift Mr. Brownlee is trying to lift shingles to the top of his roof. shingles to the top of his roof. Each bundle weighs 200 N Each bundle weighs 200 N (Output Force). He sets up a (Output Force). He sets up a pulley system that reduces his pulley system that reduces his input force to 40 N. What is the input force to 40 N. What is the MA of the pulley system?MA of the pulley system?

Wednesday, November 5Wednesday, November 5thth Entry TaskEntry Task

A machine has an input A machine has an input force of 150 N and a force of 150 N and a mechanical advantage mechanical advantage of 0.5. What is the of 0.5. What is the output force?output force?

Please have on desk:Please have on desk:• 14.1 Notes14.1 Notes• Mech Adv MathMech Adv Math

Homework:Homework:• Read 14.2Read 14.2

Objective:Objective: I will I will demonstrate my demonstrate my understanding of 14.1understanding of 14.1

Schedule:Schedule:• Review MA and Review MA and

Efficiency MathEfficiency Math• 14.1 Quiz14.1 Quiz

Thursday, November 6Thursday, November 6thth Entry Task Entry Task

A person is doing A person is doing 1000 joules of work 1000 joules of work on a hammer to pry on a hammer to pry up a nail. The up a nail. The hammer does 925 hammer does 925 joules of work on the joules of work on the nail to pull it out of nail to pull it out of the wood. What is the wood. What is the efficiency of the the efficiency of the hammer?hammer?

Schedule:Schedule:• Inclined plane notes and Inclined plane notes and

mathmath• Inclined plane activityInclined plane activity

Homework:Homework:• Complete activity if not Complete activity if not

finished in classfinished in class

Objective:Objective: I will calculate I will calculate the mechanical advantage the mechanical advantage of an inclined planeof an inclined plane

Please have on Desk:Please have on Desk:• Pencil, journalPencil, journal

Inclined Plane

• Have you ever had to lift something from a lower level to a higher level?

• The job is much easier if you have a ramp. • For example, a ramp makes it much easier to

push a grocery cart over a curb. • A ramp is an example of a simple machine

called an inclined plane. • An inclined plane is a flat, sloped surface.

How It Works• An inclined plane allows you to exert your input

force over a longer distance. • As a result, the input force needed is less than

the output force. • The input force that you use on an inclined plane

is the force with which you push or pull an object.

• The output force is the force that you would need to lift the object without the inclined plane.

• Recall that this force is equal to the weight of the object.

Mechanical Advantage

• You can determine the ideal mechanical advantage of an inclined plane by dividing the length of the incline by its height.

• Ideal Mechanical Advantage =

Length of Incline ÷ Height of Incline

• For example, if you are loading a truck that is 1 meter high using a ramp that is 3 meters long, the ideal mechanical advantage of the ramp is 3 meters ÷ 1 meter, or 3.

• The inclined plane increases the force you exerted three times.

• If the height of the incline does not change, increasing the length of the incline will increase the mechanical advantage.

• The longer the incline, the less input force you need to push or pull an object.

• Although the amount of work is the same whether you lift the boxes or push them up the ramp to the truck, you need less force when you use an inclined plane.

• When you use a ramp, what happens to the distance over which you exert your force?

Wedge

• If you’ve ever sliced an apple with a knife, pulled up a zipper, or seen someone chop wood with an ax, you are familiar with another simple machine known as a wedge.

• A wedge is a device that is thick at one end and tapers to a thin edge at the other end.

• It might be helpful to think of a wedge, like the one shown below, as an inclined plane (or sometimes two inclined planes back to back) that can move.

The Forces on a Wedge

• The input force exerted on a wedge results in output forces that can split the log.

• You have probably never given much thought to the zippers on your clothes.

• But zippers use wedges to push the two sides apart.

How It Works• When you use a wedge, instead of moving an

object along the inclined plane, you move the inclined plane itself.

• For example, when an axe is used to split wood, the axe handle exerts a force on the blade of the axe, which is the wedge.

• That force pushes the wedge down into the wood.

• The wedge in turn exerts an output force at a 90° angle to its slope, splitting the wood in two.

• Wedges are a part of your everyday life. For example, a zipper depends on wedges to close and open.

• A pencil sharpener, a cheese grater, and a shovel all make use of wedges.

Mechanical Advantage

• The mechanical advantage of the wedge and the inclined plane are similar.

• The ideal mechanical advantage of a wedge is determined by dividing the length of the wedge by its width.

• The longer and thinner a wedge is, the greater its mechanical advantage.

• For example, the cutting edge of a steel carving knife is a wedge.

• When you sharpen a knife, you make the wedge thinner and increase its mechanical advantage.

• That is why sharp knives cut better than dull knives.

Friday, November 7Friday, November 7thth Entry TaskEntry Task

Explain the Explain the force/distance trade-off force/distance trade-off that allows an inclined that allows an inclined plane to help people do plane to help people do work.work.

Schedule:Schedule:• Lever notesLever notes• Math practiceMath practice

Objective: Objective: • I will calculate the I will calculate the mechanical advantage of mechanical advantage of a levera lever

HomeworkHomework• Complete the math Complete the math

practice if not finished practice if not finished in classin class

Please have on Desk:Please have on Desk:• Inclined plane activityInclined plane activity• Journal and pencilJournal and pencil