Unit VII Machines

Conceptual Physics - Machines
Day 1 | Day 2 | Day 3 | Lab | Reading Assignment

This Unit's
Process Standards: 1.1, 1.2, 1.3, 3.3, 3.5, 4.1, 4.2, 4.4, 4.5, 5.2, 6.1, 6.2, 6.3
Content Standards: 2.1, 2.2, 3.1
Instructional Technology Standards: 2.1, 4.1, 4.2, 4.3, 4.4

This Unit's	Process Standards: 1.1, 1.2, 1.3, 3.3, 3.5, 4.1, 4.2, 4.4, 4.5, 5.2, 6.1, 6.2, 6.3 Content Standards: 2.1, 2.2, 3.1 Instructional Technology Standards: 2.1, 4.1, 4.2, 4.3, 4.4


Simple machine Inclined plane Wedge Screw Lever	Fulcrum 1^st class lever 2^nd class lever 3^rd class lever Pulley	Fixed pulley Movable pulley Pulley system Wheel and axle Compound machine

Machines: change the size and direction of a force.

Machines make work easier or faster, but never produce more work than is put into them. In fact, because of friction, more work is put into a machine than comes out!

What type of simple machine is a knife?

Types of machines: simple or compound.

Simple machines do work with one movement.

There are 6 simple machines.

Inclined plane a slanted surface used to raise an object.
Work is made easier because the effort force moves over a greater distance.
Mechanical advantage is equal to the length of the plane divided by its height.

Wedge a moving inclined plane.
Force is multiplied since it is applied to a wide area and exerted over a small area.
The "sharper" the wedge, the greater the mechanical advantage.

Screw an inclined plane wrapped around a cylinder.
Multiplies an effort force by acting through a long effort distance.
The closer the threads on a screw, the greater the mechanical advantage.

Computer Assignment 261:
This assignment must be finished by the end of class today to receive credit.
Scoring criteria

Drag and drop the picture here onto a Microsoft Word page.

Center the picture on the page.
Use WordArt to put the heading "Simple Machines" at the top of the page.
Use Word art to name the simple machines represented by each tool pictured.

Copy and paste the bold print in the tip at the top of this page below what you have done on the Word page.

Change the font to "sand" and enlarge to fill most of the remaining space on the page.
Place a rectangle with a 3 point line around the text.

Day 2

"Give me a place to stand and I will move the Earth."

What type of lever is a baseball bat?

Lever a bar which can move freely around a fixed position, or fulcrum.
First-class lever

Fulcrum is between EF and RF
Multiplies EF and changes its direction

Experiment with a first-class lever.
Second-class lever

RF is between fulcrum and EF
Multiplies EF, but does not change its direction

Third-class lever

EF is between fulcrum and RF
Does not multiply force
Multiplies the distance the effort force travels

Calculate the mechanical advantage of any lever by dividing effort arm length by resistance arm length.

Pulley a belt, rope, or chain wrapped around a wheel.

Fixed pulley

Does not multiply force.
Changes the direction of the effort force.
Mechanical advantage is equal to one.

Movable pulley

Multiplies effort force but cannot change direction of the effort force.
Mechanical advantage is the effort distance divided by the resistance distance.

Pulley system

A combination of fixed and movable pulleys.
Mechanical advantage is equal to the number of supporting ropes.

Experiment with pulleys.
Wheel and axle a lever that rotates in a circle around an axle.
Two wheels of different sizes connected - the axle being the smaller wheel.
EF applied to the wheel is multiplied at the axle.

With your table, do the following:

Given a 100 gram mass, a spring scale, one small pulley, and a piece of twine - prove that a fixed pulley does not multiply an effort force, while a movable pulley does.

Day 3

Compound machines:
combinations of two or more simple machines.

What two simple machines make up scissors?

Machine Tool
Programmer

Concept Understanding:

Find out how gears work.

What are the four main reasons gears are used?
Two gears are turning together. One has 40 teeth, the other has 10. What is the "gear ratio"?

Look at this diagram of a lever. If the distance from E to F is 60 inches and the distance from R to F is 20 inches, What is the mechanical advantage of the lever?
Name five places on a bicycle where bearings are used to reduce friction.

Computer Activity:

Paste this picture onto a Word page.
If not already open, open the "drawing" toolbar.
Use the "freeform" and "fill" tools to color the picture.

Show the colored picture to your science facilitator.
Do not print!

Research Links:

Spotlight On Simple Machines - Franklin Institute
The Elements of Machines - Inventors Toolbox, Museum of Science, Boston
How Stuff Works - By Marshall Brain

Simple Machines for Kids - by Appliance Parts Pros

Physical Science

A knife is an example of a wedge.

A baseball bat is an example of a third-class lever.

Scissors are made up of two first-class levers.