Drexel-SDP GK-12 LESSON
Chute-ing Among the Stars
Subject Area(s)
Measurement, Number & Operations, Physical Science, Problem
Solving, Science and Technology
Lesson Title
Chute-ing Among the Stars
Grade Level
7 (6-12)
Time Required
25 mins
Summary
The background and motivation for the design and use of parachutes is presented to elicit
students’ interest in the associated activity, Ah Chute, wherein students test different designs of
parachutes. Concepts presented in this lesson include fluids and particle kinetics that contribute
to the overall effect of air resistance that we attribute to the function of a parachute.
Engineering Connection
Parachutes demonstrate a tangible example of fluid flow around an object. Though we
may not regularly consider the effect of air on an object’s motion, fluids may contribute
significant forces on objects with large exposed surface areas.
Fluid effects due to the forces associated with the relative motion of an object in a fluid,
otherwise known as drag, are considered in the design of an object. Designs that are subjected
to drag forces in air or other gases, known as aerodynamics, can be easily found in the aerospace
industry (rockets, missiles, aircraft, spacecraft), cycling (helmets, bicycles), and sports (baseball,
football). The response of a moving object in a liquid environment, hydrodynamics, is
considered in marine designs (submarines, boat hulls and trim tabs) and competitive swimming
(“shark-skin” suits), while the action of a moving fluid can produce significant effects in
geological (riverbed dredging of sandbars, alterations of current for Palm Islands in Dubai) and
biological (shear stress in pulmonary and cardiovascular) systems.
Keywords
parachute, fluid dynamics, air resistance, drag
Educational Standards
 PA Science:
o 3.1.7 – Unifying themes
o 3.2.7.B – Apply process knowledge to make and interpret observations
o 3.2.7.D – Know and use the technological design process to solve problems
 PA Math:
o 2.1.8.D – Apply ratio and proportion to mathematical problem situations
involving distance, rate, time, and similar triangles
o 2.3.5.D – Convert linear measurements within the same system
o 2.4.5.B – Use models, number facts, properties, and relationships to check and
verify predictions and explain reasoning
o 2.5.8.B – Verify and interpret results using precise mathematical language,
notation and representations, including numerical tables and equations, simple
algebraic equations and formulas, charts, graphs, and diagrams
o 2.5.8.C – Justify strategies and defend approaches used and conclusions reached
o 2.7.8.D – Compare and contrast results from observations and mathematical
models
o 2.8.8.B – Discover, describe, and generalize patterns, including linear,
exponential, and simple quadratic relationships
Pre-Requisite Knowledge
Background of Newton’s laws and concept of gravitational acceleration may aid engagement,
but is not considered necessary.
Learning Objectives
After this lesson, students should be able to:
 Identify gases and liquids as fluids
 Discuss how a fluid acts on an object (relative motion, surface area)
 Relate principles of aerodynamics and hydrodynamics to designs of aircraft and watercraft
Introduction / Motivation
If a startup activity is required or preferred, have students answer some introductory questions:
1. What is a parachute and what is its function?
2. How does a parachute operate?
3. Where have you seen a parachute deployed?
Review and discuss the responses to start introduction.
A parachute appears as though it is an inverted plastic bag that captures air. After being
deployed, its function is to decrease the speed that something is falling. We’re familiar with
parachutes being used by skydivers, but parachutes are used by the military and humanitarian
missions to airdrop supplies in areas that do not have suitable landing areas.
When an opened parachute captures air, it is subjected to air resistance. In engineering, we
classify forms of matter that are not solids - gases and liquids – as fluids. At certain temperature
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and pressure conditions, fluids are characterized by specific densities and viscosities. Density is
how much matter is packed into a given space; viscosity is a measure of its resistance to
movement. An important consideration for fluids is their compressibility – when their density
increases (and more matter can be packed into the same space). Ask for a show of hands on
whether air and water are compressible. After getting results, point out that compressed air is
used (i) in construction – pneumatic tools, (ii) electronic air sprays, (iii) SCUBA. Water does
not compress unless subjected to very high pressures (which is a good thing, since our bodies
are mainly composed of water).
The resistance that fluids impart to objects moving relative to it is called drag. Sometimes
engineers seek to minimize drag. Automakers test aerodynamic designs using smoke-flow
visualization. One-piece bathing suits are no longer being worn just by women: competitive
swimmers have started to wear full-body swimsuits that decrease drag forces in water. Other
times – namely when quick deceleration is necessary – we take advantage of drag forces, which
scale with the relative velocity of an object in fluid. Upon landing, space shuttles deploy a
parachute and airplanes raise panels and lower flaps on the wings. These actions create a greater
surface area for the fluid to act upon and resist.
An interesting phenomenon resulting from physics is the occurrence of terminal velocity. If
an object is in free-fall and no drag forces are acting upon it, constant gravitational acceleration
will continue to increase its downward velocity. Drag acting upon an object in free-fall provides
an opposing force that diminishes the downward acceleration. When the forces imparted by drag
and gravity (i.e. weight) are equal, the net acceleration is zero, and the object’s downward
velocity remains constant. Deploying a parachute which has a surface area greater than the
object will increase the effective drag force and contribute to an overall decrease in downward
velocity. Skydivers deploy parachutes at a certain altitude so that their speed decreases to the
point where a safe landing is possible.
Lesson Background & Concepts for Teachers
References for projectile motion covering free-fall and one-dimensional kinematics are widely
available on the internet and physics textbooks.
Vocabulary / Definitions
Word
Definition
fluid
Forms of matter that are not classified as solids. Gases and liquids are fluids,
characterized by their inability to resist deformation and ability to flow.
drag
A force resulting when there is relative motion between a fluid and an object; the
force acts on the surface of the object and scales with that surface’s area and
relative velocity between the fluid and object.
terminal
The maximum velocity that may be achieved in free-fall as a result of drag forces
velocity
balancing gravitational forces.
Associated Activities
Ah Chute!
Lesson Closure
The associated activity, Ah Chute!
Assessment
3
Pre-Lesson Assessment
Embedded – introductory questions and discussion about parachutes (optional)
Additional Multimedia Support
Lesson_ChuteingAmongStars_Media.zip contains the following files:
Fluid Mechanics – airfoil.mp4: Flow visualization around airfoil, originally downloaded
from http://www.youtube.com/watch?v=7jTeiz_f1iY
Fluid Mechanics – Cool science experiments.mp4: Flow visualization around circular
cylinder, originally downloaded from
http://www.youtube.com/user/guiathome#p/c/BD6071B837419278/17/gbDscDSUAg4
Owner
Drexel University GK-12 Program
Contributors
John C. Fitzpatrick, Mechanical Engineering and Mechanics, Drexel University
Copyright
Copyright 2010 Drexel University GK-12 Program. Reproduction permission is granted for nonprofit educational use.
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