GROUP SIZE: Large
TIME: 60 minutes
TYPE OF ACTIVITY: Discussion and Student Investigation
TEACHING STRATEGY: Guided Discovery Expository
CONCEPTS: g Forces Gravity weightless
SKILLS: Hypothesizing Inference Collecting Data
Objectives: To provide an approximation of what it feels like in a weightless atmosphere; to relate earthbound activities to space activities.
Materials: Activity sheet (following lesson); graph paper; water bucket with water.
Procedure: 1. Before getting into a discussion of weightlessness in space, ask your students to- imagine taking a bucket and filling it part way with water and swinging it over their heads. What will happen? Get the bucket and begin swinging the bucket back and forth. What happens to the water? Now, swing the bucket completely around over your head. What do the students observe about the water? Is it falling up into the bucket? Why? (anti-gravity)
2. Have the students imagine riding an elevator while standing on a bathroom scale. This is a thought experiment, so ask them to really get in touch with feelings they have experienced in elevators and then start them at the top floor. Ask them to imagine they are on the 20th floor standing on a scale. They push the button for the basement. What will happen to the reading on the scale? How long will this wonderful diet go on? What happens when the elevator slows down for its basement stop? (gain weight slightly) What happens when the elevator comes to a complete stop? (back to normal weight) Why does all of this happen?
3. If they are having trouble figuring it out, have them image jumping off a diving board while sitting on the scale. What would the scale read as they fly through the air? What can this be compared to?
4. Discuss some of the times when a person could feel what it’s like to be “weightless.” Free-falling from a plane, just after a person crests a hill in a car, diving in a parabolic arc in a plane, are three examples. If no one mentions some of the rides at the amusement park, bring them up: the roller coaster, the free fall (Demon Drop or Texas Cyclone), the rotor, the parachute drop and the Enterprise or the wheelie.
As you discuss some of these rides, talk about when the rider is falling down, falling up, is weightless or is pulling more g’s than usual.
A. Roller Coaster:
What happens when you suddenly drop over the crest of a big roller coaster? What do you imagine your weight is at that point? what happens to the stomach in the valley of the roller coaster? Why? (Because you can go so fast, you can feel 3 g’s and that’s what astronauts pull at blast off of the Space Shuttle.) When you are back up again and have reached the second hilltop, what can you expect to feel at the peak? Do you know what this free fall curve is called? (parabola) What happens when you’re in a roller coaster with loops? (You fall up, just like the water in the bucket.) If you had a ball tied to string that was tied to your wrist, what would happen to it as you fell up?
B. The Enterprise or Wheelie:
This ride is almost a life-size version of the water bucket experiment. The bucket is now a padded car and the person gets to play the water. The rope attached to the bucket is replaced by a set of support beams that extend 25 feet from the center to the seat of each car. Ask the students to imagine the cars building up speed and tilting until riders orbit in a nearly vertical circle at a rate of 4 seconds per turn at a speed of 27 miles per hour. Why is speed so important?
What does the body pushing against the back of the car tell you about the g force? Where would the force be greatest – at the top or at the bottom? Why? Explain to the students that before the Apollo moon missions, astronauts trained on a faster version of the super-gravity machine. It was called a centrifuge. Those tests of human reactions to g forces provided the data to guarantee that the wheelie is a safe ride. (Another “spin-off” from the Space Program!?!) Ask how the students might relate this ride to giant space stations orbiting the earth. How could the concept be used that way? Where on this spinning station, would it be most comfortable for people to walk about?
C. The Rotor:
This is a turning barrel with a floor that drops down about a foot once the 12.5 foot barrel is spinning at full speed. Why do they have to wait until it has sped up? It turns at about 35 turns per minute – about the rate of a long playing record – and produces a g force of over 2.5. Why are 2.5 g’s necessary to this ride? What happens when the floor drops away? Why don’t all the people fall down? How could this concept be used for space vehicles orbiting in space?
- 5. Hand out the activity sheet and talk about the Demon Drop or Texas Cliffhanger free fall ride.
where does weightlessness occur? Where would they feel the largest number of g forces? Make sure your students understand the way the ride works so the data recorded will make sense to them. There are two parts to the activity. (a) Have the students use the first page of the activity sheets to do a graph of the two persons’ pulse rates; and (b) have the students complete the answers on the second page of the activity sheets. Discuss with them, the physiological and the psychological ramifications of rides such as these. How do those ramifications relate to astronauts in space or, indeed, to any of us who might someday live and work in space?
Extension: Talk with the students about what other kinds of data one could collect at an amusement park and the ways the data could be recorded and then analyzed. (Things like: What’s the most popular ride? What’s the average wait time on specific rides? What’s the most common comment made by people as they come off a particular ride? How many people come to the park in an hour on average? What’s the ratio of adults to children etc., etc.?) Talk about how important some of that information could be to the park owners and managers and how they use information like that. Make plans to visit an amusement park with your students, armed with specific questions you want answered and a scientific method to obtain those answers.
Joan Prukop is a 30 year old physical science teacher riding the Texas Cliffhanger (Cedar Point calls it the Demon Drop) for the first time.
Katie Jackson is a 13 year old student riding the Texas Cliffhanger for the second time (the first time on the recording day).
1. Where on the ride does Katie’s pulse rate peak?
2. Where does Joan‘s pulse rate peak?
3. Offer a possible explanation for the difference
4. Which rider’s pulse rate drops back to normal more quickly?
5. In this ride, does the anticipation of the drop seem to cause pulse rates to rise?
6. What seems to be the effect on pulse rates of moving the riders slowly toward the drop? (points C-D)
7. What is the pulse gain for Joan? (% gain) What is the pulse gain for Katie? (% gain)
8. What variables are there here that should be considered when com- paring the two recordings? Can you make any generalizations from from these two pieces of data?
9. Which ride at an amusement park seems the most fear-inducing to you? Why do you think you feel as you do?