Simple Machines
A Professional Development
Module for Middle School Physical
Science Teachers
Presented by
y Melanie Kirkham and Donna Whiting.
g
Purpose of this Module
• First and foremost, to help you fine-tune
your skills for a more effective and
rewarding classroom experience.
y
Specifically:
• To work on content and teaching
techniques to prepare you for more specific
and in-depth treatment of energy and
simple machines.
Presented by Melanie Kirkham and Donna Whiting
2
Module Goals
• Provide a content overview of the big ideas in the APS
Enhanced Scope and Sequence for Physical Science.
• Study
S
the GPS
G S Framework Unit Key Vocabulary,
Essential Questions, Enduring Understandings, and
Concept Maps for Physical Science.
• Complete some of the Physical Science GPS Framework
Unit tasks.
• Share ideas about implementation of the Physical
Science GPS Framework Unit tasks.
• Discuss perceptions of the challenges teachers face
regarding Physical Science content
content.
Presented by Melanie Kirkham and Donna Whiting
3
Module Structure
This 3-hour session will be structured around
the 5E Instructional Model
Model.
• The 5Es provide a format for lessons that
build on what students already know
know.
• We hope that you consider approaching
your lessons in a similar way.
Presented by Melanie Kirkham and Donna Whiting
4
Background
Energy
• Energy can be defined as the ability to do
work.
work
• There are two basic classifications of
energy:
• Potential energy is due to the position and
state of an object
object.
• Kinetic energy is due to the motion of an
object.
object
Presented by Melanie Kirkham and Donna Whiting
6
Types of Energy – 1
• Heat
• Measured by temperature
temperature.
• Light
• Includes all forms of electromagnetic radiation,
such as X-rays and microwaves, as well as
light.
light
• Electricity
• Due to the flow of electrons.
• Sound
• Due to vibration of particles.
Presented by Melanie Kirkham and Donna Whiting
7
Types of Energy – 2
• Mechanical Motion
• Due to position and/or motion of objects
objects.
• Chemical*
• Due to bonds between atoms.
• Elastic*
• Due to compression of a spring.
Presented by Melanie Kirkham and Donna Whiting
8
Energy of Mechanical Motion
• An apple hanging in the
tree has potential energy
due to its height above
the ground.
• When the stem breaks,
gravity makes the apple
fall.
• As it falls, the potential
energy is
i ttransformed
f
d
into kinetic energy.
Presented by Melanie Kirkham and Donna Whiting
9
Energy Transformations
• Energy can be transferred between
different types.
types
Light bulbs transform
electricity into light.
Fire transforms chemical energy
in the wood into heat and light.
Presented by Melanie Kirkham and Donna Whiting
10
Law of Conservation of Energy
Energy can never be created or
destroyed; it can only be transformed
between different forms.
Presented by Melanie Kirkham and Donna Whiting
11
What is a Simple Machine?
• Simple machines use a single force to help
a person do work
work.
• Work is the product of a force applied to an
object and the distance it is applied
applied.
work = force × distance
• The work done by a simple machine is the
same as the work put into it.
Presented by Melanie Kirkham and Donna Whiting
12
Simple Machines and Work
work = force × distance
• Simple machines allow us to:
• Apply a smaller force over a greater distance.
• Or, apply a greater force over a smaller
distance.
di
• And, change the direction of the force.
Presented by Melanie Kirkham and Donna Whiting
13
The Six Simple Machines
lever
pulley
inclined plane
wedge
g
screw
wheel & axle
Presented by Melanie Kirkham and Donna Whiting
14
Lever
• Consists of beam rotating about a
fulcrum and a supported load
load.
• Can reduce force or distance required
depending on location of fulcrum and
load.
• Examples:
• scissors
• nutcracker
• fishing rod
Presented by Melanie Kirkham and Donna Whiting
15
Lever Classes
• Class 1 – fulcrum in middle
• Changes direction,
direction multiplication
of force or distance depends on
length of arms.
• Class 2 – load in middle
• Less force
force, more distance
required.
• Class 3 – force in middle
• Less distance, more force
required
required.
Presented by Melanie Kirkham and Donna Whiting
16
Pulley
• Consists of cable running in grooved
wheel.
wheel
• Can change direction of force and/or
reduce force required
required.
Presented by Melanie Kirkham and Donna Whiting
17
Pulley Classes
• Class 1 – fixed pulley
• Axle of pulley is fixed in space
space.
• Changes direction of force.
• Does
D
nott reduce
d
fforce.
• Class 2 – moveable pulley
• Axle of pulley is attached to load.
• Reduces force required.
• Combined – multiple fixed and moveable
• Block and tackle.
Presented by Melanie Kirkham and Donna Whiting
18
Inclined Plane
• Can lift a load with less force, but requires
greater distance.
distance
• Changes direction of force.
• Examples:
• interstate on-ramp
• loading ramp
Presented by Melanie Kirkham and Donna Whiting
19
Wedge
• Consists of moving inclined
plane.
plane
• Changes direction of force.
• Can be used to split two parts.
• Example: axe
• Can also be used to hold
g in p
place.
something
• Examples: doorstop
Presented by Melanie Kirkham and Donna Whiting
20
Screw
• Consists of inclined plane wrapped around
cylinder.
cylinder
• Converts rotational force to linear force.
• Examples:
• vending machine
• Archimedes screw
Presented by Melanie Kirkham and Donna Whiting
21
Wheel & Axle
• Two connected parts with same rotation
axis and different radii
radii.
• Like a rotational lever.
• Converts smaller force and larger distance
on wheel to larger force and smaller
distance on axle.
• Examples:
• steering wheel
• door handle
Presented by Melanie Kirkham and Donna Whiting
22
Mechanical Advantage – 1
• Mechanical advantage is a measure of the
effectiveness of the simple machine
machine.
• How much it multiplies the force.
• Ratio of output force to input force
force.
• Since work (= force x distance) does not
change:
h
• MA is also ratio of input distance to output
di t
distance.
Presented by Melanie Kirkham and Donna Whiting
23
MA of Levers and Wheel&Axles
3m
10 kg
3m
10 kg
MA = 10 kg / 10 kg
=3m/3m=1
1m
4m
2m
4m
10 kg
5 kg
MA = 10 kg / 5 kg
=4m/2m=2
MA = 4 m / 1 m = 4
Presented by Melanie Kirkham and Donna Whiting
24
MA of Planes and Wedges
Inclined Planes:
Wedges:
• Mechanical advantage
is length of slope
divided by height.
• Mechanical advantage
is length of wedge
divided by width.
2m
2m
MA = 6 m / 2 m = 3
MA = 3 m / 2 m = 1.5
Presented by Melanie Kirkham and Donna Whiting
25
MA of Screws and Pulleys
Screws:
Pulleys:
• Mechanical advantage
depends on pitch
(distance between
threads) and distance
between center and
applied force.
• Mechanical advantage is
load divided by applied
force, or, distance rope is
pulled divided by distance
load is lifted.
50 mm
5 mm
MA = 2π ∗ distance / pitch
= 2π ∗ 50 mm / 5 mm = 63
5 kg
10 kg
10
MA = 1
Presented by Melanie Kirkham and Donna Whiting
10
MA = 2
26
Complex Machines
• Combine multiple simple machines to
simplify a task.
task
• Example: car jack
• Combines
C bi
wheel
h l & axle
l and
d screw.
Presented by Melanie Kirkham and Donna Whiting
27
Rube Goldberg Machines
• Fantastical and very complex machine that
accomplishes a simple task
task.
• Based on cartoons drawn by Rube
Goldberg (1883
(1883-1970).
1970)
Presented by Melanie Kirkham and Donna Whiting
28
Engage
Presented by Melanie Kirkham and Donna Whiting
29
Engage
• Watch the Honda “Cog” video.
• http://www.youtube.com/watch?v=rYabfifhEPE
p
y
• Other Rube Goldberg videos:
• Officeplace Contraption
http://www.youtube.com/watch?v=0J16dyV4Du8
• Japanese Ramen Cooking Contraption
http://www.youtube.com/watch?v=1kvdq8cRNBM
p
y
q
• Curtain Opener
http://www.youtube.com/watch?v=RouXygRcRC4
Presented by Melanie Kirkham and Donna Whiting
30
Explain
Presented by Melanie Kirkham and Donna Whiting
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Explore
Presented by Melanie Kirkham and Donna Whiting
32
Construct Rube Goldberg Mach.
• Construct a Rube Goldberg machine.
• Goal:
Goal Raise a flag
flag.
• Include at least three types of simple
machines.
• Only touch the machine once, to start it.
Presented by Melanie Kirkham and Donna Whiting
33
Materials
•
•
•
•
•
•
•
base
round wood dowels (5)
wood strips (3)
connector strips (10)
connector blocks (10)
pieces cardstock (5)
screws (4)
•
•
•
•
•
•
•
large pulley (1)
small pulley (1)
large gear (1)
small gear (1)
marbles (3)
toy car (1)
plastic cups (2)
String wire and plastic tubing (slide stop material) also available
String,
available.
Presented by Melanie Kirkham and Donna Whiting
34
Engineering Design Process
Define problem
General
information
Specific
information
Gather information
Design solution
Build solution
N
No
Test solution
Y
Yes
Presented by Melanie Kirkham and Donna Whiting
Present results
35
Design Process - 1
• Define the problem:
• Review goal as assigned by the teacher
teacher.
• To construct a Rube Goldberg machine that will
raise a flag using as many simple machines
and steps as possible.
• Gather information:
• General information about simple machines,
forces and energy.
• Specific information about the materials and
tools available.
Presented by Melanie Kirkham and Donna Whiting
36
Design Process - 2
• Design solution:
• Brainstorm a variety of possible steps
steps.
• Draw a rough picture of the proposed
machine.
machine
• Measure and layout pieces to make sure
everything fits
fits.
• Build solution:
• Tips
• Start from the last step and build forward.
• Measure twice and cut once
once.
Presented by Melanie Kirkham and Donna Whiting
37
Design Process – 3
• Test solution:
• If some parts don’t
don t work,
work redesign them
them.
• If it all works, GREAT, then …
• Present
P
t results:
lt
• Demonstrate your Rube Goldberg machine to
th class.
the
l
• Point out all the simple machines and
calc late their mechanical ad
calculate
advantages.
antages
• Turn in documentation to the teacher.
Presented by Melanie Kirkham and Donna Whiting
38
Crazy Contraptions
• Rube Goldberg kits available from Teacher
Geek (http://www
(http://www.teachergeek.com).
teachergeek com)
• Includes connector strips, dowels, wood
strips wheels
strips,
wheels, pulleys
pulleys, gears
gears, marbles
marbles, etc
etc.
• Plywood bases available.
Presented by Melanie Kirkham and Donna Whiting
39
Alternative Materials List
•
•
•
•
•
•
•
•
•
String
Tape
Rubber bands
Craft sticks
Marbles
Eye screws
Pencils
Pl ti cups
Plastic
Adhesive/poster putty
•
•
•
•
•
•
•
•
Pegboard
Wood dowels
Heavy card stock
Paper clips
Thumb tacks
Pennies
Straws
C li d i l containers
Cylindrical
t i
(film canisters, etc.)
Presented by Melanie Kirkham and Donna Whiting
40
Extend
Presented by Melanie Kirkham and Donna Whiting
41
Options
• Students write a report on the history of
Rube Goldberg machines
machines.
• Students draw a Goldberg-like cartoon of
their machine.
machine
• Students prepare technical drawings of
their machine.
• Students dissect a complex machine (e.g.
car jack), pointing out the simple machines
in it.
Presented by Melanie Kirkham and Donna Whiting
42
Evaluate
Presented by Melanie Kirkham and Donna Whiting
43
Performance Evaluation
• Students demonstrate their Rube Goldberg
device.
device
• Students describe their device, pointing out
all the simple machines and calculate their
mechanical advantages.
• Students explain how they designed and
built their device.
Presented by Melanie Kirkham and Donna Whiting
44