CHAPTER INVESTIGATION
Design a Machine
OVERVIEW AND PURPOSE
Although simple machines were developed thousands of years
ago, they are still used today for a variety of purposes. Tasks such
as cutting food with a knife, using a screwdriver to tighten a
screw, and raising a flag on a flagpole all require simple machines.
Activities such as riding a bicycle and raising a drawbridge make
use of compound machines. In this investigation you will use
what you have learned about simple and compound machines to
• choose a machine to design
• build your machine, test it, and calculate its mechanical
advantage and efficiency
Procedure
Make a data table like the one shown on page 177.
MATERIALS
• 500 g object
• 100 g object
• meter stick
• spring scale
• pulleys with rope
• board
• stick or pole
From among the three choices listed below, choose which
problem you are going to solve.
Carnival Game You work for a company that builds carnival
games. Your supervisor has asked you to build a game in which
a simple machine moves a 500-gram object from the bottom of
the game 1 meter up to the top. This simple machine can be
powered only by the person operating the game.
Video Game Contest The marketing department of a video
game company is holding a contest. Candidates are asked to
submit a working model of a compound machine that will move
a 500-gram object a distance of 1 meter. The winning design will
be used in a new video game the company hopes to sell. This
compound machine must include at least 2 simple machines.
Construction Company You work
for a construction company. Your
boss has asked you to design a
machine for lifting. Your first step
is to build a scale model. The model
must be a compound machine with a
mechanical advantage of 5 that can
move a 500-gram object a distance of
1 meter. You also can use a 100-gram
object in your design.
176 Unit 1: Matter and Energy
Brainstorm design ideas on paper. Think of
different types of machines you might want
to build. Choose one machine to build.
Write
Conclude
It Up
1. INFER How might changing the arrangeBuild your machine. Use your machine to
perform the task of moving a 500-gram
object a distance of 1 meter.
If you chose the third problem, test your
compound machine to determine if it has
a mechanical advantage of 5. If not, modify
your machine and retest it.
Record all measurements in your data table.
Observe and Analyze
ment of the parts in your machine affect the
machine’s mechanical advantage?
2. IDENTIFY LIMITS What was the
hardest part about designing and constructing
your machine?
3. APPLY If you needed to lift a large rock
from a hole at a construction site, which type
of simple machine would you use and why?
Which type of compound machine would
be useful?
Write
It Up
1. RECORD OBSERVATIONS Make a
sketch of your machine.
2. CALCULATE Use your data to calculate
the mechanical advantage and efficiency of
your machine. Use the formulas below.
Output Force
Mechanical Advantage = Input Force
Work
out
Efficiency (%) = p 100
Work in
3. ANALYZE
Carnival Game Add arrows to the drawing
of your machine to show the forces involved
and the direction of those forces. If your goal
was to move the ball from the top of the
game to the bottom at a constant speed,
how would your machine and diagram have
to be changed?
Video Game Contest Does your machine
change the size of the force, the direction
of the force, or both? If you used a pulley
system (two or more pulleys working together),
describe the advantages of using such
a system.
Construction Company Determine whether
force or distance is changed by each simple
machine in your compound machine. In what
ways might you improve your machine to
increase its efficiency?
INVESTIGATE Further
CHALLENGE If you made a simple machine,
how would you combine it with another simple
machine to increase its mechanical advantage?
If you made a compound machine, redesign it to
increase its efficiency or mechanical advantage.
What made the difference and why?
Draw a plan for the new machine. Circle the
parts that were changed. If you have time, build
your new machine.
ne
Design a Machi
nalyze
Observe and A
Data
Table 1. Machine
ut force
Output force Inp
Output work
Input work
Mechanical
Advantage
Efficiency
Sketch
Chapter 5: Forces and Machines 177