Hands-on Activity: Egg-cellent Landing
Educational Standards :
Pre-Req Knowledge (Return to Contents)
Learning Objectives (Return to Contents)
After this activity, students should be able to:
Materials List (Return to Contents)
Each group should have:
For each class:
Introduction/Motivation (Return to Contents)
Through careful design and many experimental trials, NASA engineers have developed a way to safely land Mars rovers when approaching the great Red Planet at speeds exceeding 12,000 mph. To slow down the spacecraft that is transporting the rover, engineers have designed a craft that includes an aeroshell, which in turn in comprised of a heat shield, a parachute, airbags, rockets and lander , among other important components. Once the heat shield has done its part in effectively bringing the lander to a vertical stop 40 to 50 feet above the ground, the bridle that tethers the lander to the aeroshell's backshell is cut, and the lander — surrounded with airbags and containing the rover inside — free falls to the Martian surface and bounces its way to a stop.
The Egg-cellent Landing activity will simulate the free-falling lander and its subsequent bouncing that occurs before it finally stops. However, since the experiment will be done on Earth and not on Mars, we can take advantage of Earth's thicker atmosphere.
Students should understand that objects accelerate as they fall. However, falling objects experience drag, which is friction caused by the atmosphere. As an object falls faster, drag increases. Eventually, the drag balances out the weight of the object and prevents any further acceleration. The object will then continue to fall at a constant speed known as its terminal velocity. A good visual example of terminal velocity is to drop an inflated balloon, which will fall at a very slow rate.
Fun Fact: Did you know that you cannot kill a mouse by dropping it out of a skyscraper because its terminal velocity is so slow that it will be relatively unharmed when it hits the ground.
Terminal velocity is affected by the aerodynamics and weight of an object. If an object is not aerodynamic, it will experience more drag than an aerodynamic object. Also, a heavier object will have a faster terminal velocity than a lighter object with the same aerodynamics. Finally, the atmosphere and gravity have a secondary affect on terminal velocity since the weight of an object will depend on the gravity, and the drag acting on the object depends on the atmosphere.
Procedure (Return to Contents)
Before the Activity
With the Students
The objective of this exercise is for students to design an egg-lander within constraints to keep an egg from breaking when it hits the ground from a significant height. The landers are allowed to bounce when they hit the ground.
Safety Issues (Return to Contents)
Be sure to have students wash their hands if they touch any broken egg.
Please do not encourage student to attempt to verify this activity's Fun Fact.
Troubleshooting Tips (Return to Contents)
Placing the raw eggs into zipper bags at the start of this activity helps minimize any nasty clean-up when the students drop their landers. When the activity is done, dispose of the eggs into an outside receptacle or a waste bin that will be emptied shortly, since raw eggs do not smell good when left out of refrigeration for a while.
Assessment (Return to Contents)
Brainstorming: In small groups, have the students engage in open discussion. Remind students that no idea or suggestion is "silly." All ideas should be respectfully heard. Ask the students:
Question/Answer: Ask the students and discuss as a class:
Activity Embedded Assessment
Velocity Calculation: Calculate an equation, and summarize student responses. Write the correct answer on the board.
Velocity = Distance ÷ Time
If it took 3.1 seconds to fall 5 feet, your answer would look like:
Show and Tell: Have the students "show and tell" to the rest of the class their egg-cellent landers that they created, explaining their work to the other students.
Velocity Evaluation: To reinforce the concept of aerodynamics and weight affecting terminal velocity, have the students predict the outcome of the following two cases.
Problem Solving: Have the students engage in open discussion to suggest solutions to questions/problems.
Activity Extensions (Return to Contents)
Calculate the terminal velocities for the two balloon scenarios in the Velocity Evaluation in the Post-Activity Assessment. Then, compare the results with the Velocity Calculation in the Activity Embedded Assessment.
Activity Scaling (Return to Contents)
ContributorsChris Yakacki, Geoffrey Hill, Daria Kotys-Schwartz, Malinda Schaefer Zarske, Janet Yowell
Copyright© 2004 by Regents of the University of Colorado.
Supporting Program (Return to Contents)Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
Acknowledgements (Return to Contents)
The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education, and National Science Foundation GK-12 grant no 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.