From: jwee@mail.arc.nasa.gov (Jan Wee)
Subject: Live From Mars Teacher's Guide Preview: Activity 1.1
Date: Fri, 04 Oct 1996 15:22:57 -0500
Dear discuss-lfm members, For your preview... Activity 1.1 from the Live From Mars Teacher's Guide. Remember, these files are *not* in final copy form but for your convenience to assist you as you prepare for the Live from Mars project. The final print version of the Teacher's Guide will be shipping by the end of next week! Jan Wee ------------------------------------------------------- Activity 1.1.A: Rocket Science 101 Teacher Background Without the mighty Saturn V rockets, there could have been no Apollo program and no humans on the Moon. Without the smaller, cheaper Delta 2 rockets, MGS and MPF would not have been affordable. Weight, cost, thrust, power... all these are critical to the exploration of our Cosmos. This set of Activities will expose your students to some fundamentals of rocket science, and some key physics principles . Simple balloon rockets, for example, offer great opportunities for students to explore the Laws of Motion. These laws were first expressed by the English physicist, Sir Isaac Newton (1642-1727). Newton's First Law: Objects at rest will stay at rest and objects in motion will stay in motion in a straight line unless acted upon by an unbalanced force. (i.e., If something is at rest (not moving), it will stay at rest unless something pushes or pulls on it -- that is, exerts a force on it. Also, if something is moving in a straight line at a constant speed, it will continue to move that way unless something pushes or pulls on it.) Newton's Second Law: Force is equal to mass times acceleration. f=ma (i.e., If you push or pull on something, that force can change the object's speed and/or direction. The greater the force, the greater can be the resulting change in the object's speed and/or direction. But, for a given force, you will have less effect on a massive object than a less massive one.) Newton's Third Law: For every action there is always an opposite and equal reaction. (which translates as: if you push on something, it will "push back" with an equal amount of force) In its simplest form, a rocket is a chamber enclosing gas under pressure. A small opening at one end of the chamber allows the gas to escape, and by so doing provides a thrust which propels the rocket in the opposite direction. There's a strong similarity between the mightiest rocket and a humble balloon. The air inside a fastened balloon is compressed by the rubber walls. The air pushes back so that inward and outward forces balance: the balloon is static. When the nozzle is released, air escapes through it and the balloon is propelled in the opposite direction. Newton's Laws in rocket motion To summarize, an unbalanced force must be exerted for a rocket to lift off from a launch pad or for a spacecraft to change speed or direction (First Law). The amount of thrust (force) produced by a rocket engine will be determined by the rate at which the mass of the rocket fuel burns and the speed of the gas escaping from the rocket (Second Law) OR if you push or pull on something, that force can change the objects speed and/or direction. The harder you push or pull, the greater the effect! The reaction, or motion, of the rocket is equal to and in the opposite direction of the action, or thrust, from the engine (Third Law). Activity 1.1.A Balloon Rockets (or bursting misconceptions) Objectives Students will explore aspects of Newton's First and Third Laws of Motion. Students will be able to describe the launch and cruise phases of the MGS and MPF missions in terms of Newton's First and Third Laws of Motion. Students will conduct controlled rocketry experiments and analyze the MGS and MPF missions in terms of the principles of rocketry. Materials (for each team of 3/4 students) several balloons which, when fully inflated, are 3 to 5 inches in diameter and 1-2 feet long (party time!) several plastic drinking straws (milk shake size) strong adhesive tape nylon fishing line stopwatch or timer metric measuring tape or meter sticks Activity 1.1.A Student Worksheet (one for each student) Mars Mission Logbooks For whole class Large printed signs of Newton's Laws of Motion Vocabulary acceleration action/reaction balanced force friction launch orbit payload rocket Engage Show students a video of a rocket or Space Shuttle being launched and continuing up into orbit (Most NASA mission films will show this) i.e., a sequence of the last stages of a Shuttle/Mir docking maneuver. Have students note any changes they observe in the rocket's speed and direction. Allow time for discussion and students' sharing of personal experiences with rockets and/or launches. Explore Procedure 1. Explain to students that they are going to become flight engineers for NASA, working in small "Rocket Science Teams", and that their mission is to investigate how rockets work. This will involve some fun experiments with rockets made from balloons and, in the process, testing Newton's famous Laws of Motion. (Along with Einstein's e=Mc2, these are some of science's "Greatest Hits" or "Holy of Holies" and we hope these hands-on Activities will give the sacred text concrete significance.) Place Newton's Laws of Motion on chalkboard. This Activity will illustrate two of these laws. 2. Demonstrate experimental procedure as outlined on Student Worksheet 1.1.A. Hand out materials, and answer student questions. Then allow Rocket Teams time to construct their rockets and complete the experiment, recording data on individual worksheets as well as collecting all the teams results on a class data sheet or chalkboard. 3. Discuss the results of the balloon rocket experiments with the students. In particular, ask the following: Did all teams obtain the same data? How can we explain the differences? When did the balloon rockets go the farthest? What caused this? (A greater unbalanced force was applied for a longer period of time.) How could they test their ideas? Why did the balloon rockets stop? (There was a counter-acting force called friction between the string and the straw.) If there was no friction between the straw and the nylon string, and no wall in the way, how would the balloon rockets behave? (They would keep accelerating until all the fuel was gone because there would continue to be an unbalanced force on the balloon.) If there was no friction between the straw and nylon string, no wall in the way, and no air resistance acting against the deflated shell of the balloon, how would the rockets behave after they ran out of fuel? (They would keep going at the final speed they had when the fuel ran out.) Which Law(s) of Motion does this activity illustrate and why? Expand/Adapt/Connect Research (using print or online sources) the Delta 2 rockets chosen by NASA for Mars Global Surveyor and Mars Pathfinder. When were these rockets designed and built? Have they been used on other space missions? What are their strengths and limitations? (check out: http://mpf.www.jpl.nasa.gov/mpf/delta.html) Activity 1.1.B: Rockets and Payloads Objective Students will investigate and predict the effect of payload on the amount of energy needed to lift a rocket vertically (thereby working with Newton's Second Law of Motion). Materials (for each Rocket Science team of 3/4 students) 2-3 large, long balloons balloon pump (available in party stores) fishing line paper clips (or pennies) 1 dixie cup straws (milk shake size) tape clothes pins metric scale Activity 1.1.B Student Worksheet (one for each student) Mars Mission Logbooks Engage Have Rocket Science Teams brainstorm what equipment they would place on MGS or MPF spacecraft. Would there be any limitations to the "payload"? (Hopefully, students will suggest that payload weight was a serious constraint to the equipment that could be carried by MGS and MPF to Mars.) Explore Procedure 1. Place large sign with Newton's Second Law of Motion on chalkboard and review the formula (force = mass times acceleration). Have students express this in more colloquial terms, until you are sure all understand the principle involved. Ask: Using the same amount of pushing force, which object could you get to accelerate faster, a Mack truck or a toy wagon? Why? (If F is equal and you have bigger M, you have to have a smaller A to keep the equation balanced.) 2. Distribute materials and Student Worksheets. Review procedure with students and answer any questions. 3. Allow Rocket Science Teams sufficient time to complete investigation and record data. 4. Call all the groups together and have them post the results of each of their trials on a data table on the chalkboard. Draw group conclusions. Note: In this experiment students first witness action-reaction. Then they vary the amount of M between the first phase and second phases of the experiments, and should see a corresponding increase in the amount of force required. Acceleration is a variable not addressed , but this should be discussed, along with the effects of not holding the string vertically which adds drag from friction, lowers acceleration and changes results, etc. 5. Have teams share the design principles which made their launches successful and then develop and contribute ideas they think could be used to create an even more successful "heavy-lift" launcher. Expand/Adapt/Connect Design an experiment to investigate the following: Can you eliminate the paper cup from the rocket and have it still carry paper clips? If each balloon costs one million dollars and you need to lift 100 paper clips, how much money would you need to spend? Can you think of a way to cut this cost? Without attaching the paper cup as a payload carrier, measure the distance the balloon travels along the string in a horizontal, vertical, and 45 degree angle. Compare and discuss the results. Go online and find information giving the specific course that MPF and/or MGS will follow to travel to Mars. How many trajectory changes will be necessary? How is the spacecraft controlled? Go online, read Field Journals and bios to find out what course you need to follow to become a rocket scientist. Explain (in writing or with illustrations) a spacecraft launch, from blast-off through entry into orbit, in terms of Newton's Laws of Motion. Make sure your explanation could be understood by a younger brother or sister! Math: Graph data from the rocket experiments. Language Arts: Write a first-person account of a rocket launch as if you were Sir Isaac Newton. Reading: Read a biography of one of the following scientists associated with rocketry: Robert Goddard, Johann Schmidlap, Isaac Newton, Wan Hu, William Congreve, William Hale, Konstantin Tsiolkovsky, Hermann Oberth. Report this person's contributions to science to your class. Social Studies: Research Robert Goddard (his boyhood hometown, Worcester, Massachusetts, will be an uplink site for the first broadcast on November 19, 1996). Research why launches are held at Cape Canaveral, Florida. Research the development of rockets from the earliest to the most current of NASA designs. Then add your own design! Present your report using computer presentation software (HyperCard, HyperStudio, etc.) Art: Design your own rocket and translate into two-dimensional drawing or three-dimensional model. Suggested URLs http://www.jpl.nasa.gov/basics http://www.nar.org