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Physical Science

Gravity and Weightlessness

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Alexander Kevin Alexander Kevin 30 Points

What are some good demonstrations to show how gravity still affects objects in space even though they appear weightless, such as astronauts floating around in the space shuttle?

Carolyn Mohr Carolyn Mohr 89208 Points

Hi, Alexander, and welcome to the discussion forums!
I found a NASA resource in the NSTA Learning Center that may be of help to you:
External Resource - Why Do Astronauts Float in Space?/
Also, there are several other resources on gravity, weightlessness, etc. in the Learning Center. Do you know how to do an advanced search for specific topics there? If not let us know. It is such a great way to find great resources and ideas for teaching specific topics.

Don Dean Don Dean 200 Points

Take a dense object, say a brick, put it in the student's palm-up hand. Have him/her feel how gravity is pulling down. Very gradually reduce the weight by lifting it. This is weight. Now have the student grip it and shake it back and forth. This is mass. Never changes. Kinesthetics and lots of drama help. Don

Patricia Rourke Patricia Rourke 45925 Points

Alexander, NASA has some great resources on low g situations and encourages teachers to move away from the term'weightlessness' or 'weightless' because there is no gravity switch to turn off. Forces due to gravitational interactions always exist, albeit there are really neat low gravity situations. First, I'll share a few resoruces and then I'll go and look for an easy and fun demo of dropping a cup and a washer connected with elasticc bands - the washer jumps into the cup due to the sharing of the same gravity field. Falling Up: How the NASA Weightless Airplane Works - this site uses info from NASA to explain the 'vomet comet' - kids love these words - and gets students to revisit their thinking about low gravity situations in space a great resource of images in low gravity situations a neat article on the physiological effects of log gravity - 'chicken feet' and bone loss affects astronauts, even on the space station some fun gravity and center of mass experiments from the University of Phoenix browse this physics demonstration site and see if anything tickles your fancy ~patty

Patricia Rourke Patricia Rourke 45925 Points

a fun 'free fall' demo Poke a hole in the bottom of a plastic 1 or 2-liter water bottle. Fill the bottle 3/4 full of colored water. Hold the bottle over a large container such as a trash can and observe the water dropping out of the hole. Now from a good height over the trash can, drop the bottle into the container. ** Before you do this, ask the students to predict what they think will happen as you drop the bottle of water. Hold the bottle for a second so that the students can see the water pouring out of the hole and then drop it. What did the students observe? ( the water and the bottle fall together in the same gravity field so that no water spills out of the hole ) While in freefall, the absence of a difference in pressure will stop the water from pouring out. Second demo: get a small pail such as a child's sand pail attach a strong string or light rope to the exact center of the handle and secure it so that the rope does not move around fill the pail half way with water make the students predict what they think will happen if you twirl the pail in a vertical circle twirl the pail in a vertical circle A pail of water is whirled in a vertical circle without spilling the water when the central acceleration is greater than or equal to the gravity. Note: practice this several times so that you know how fast to twirl the pail and not get wet - don't make the students laugh at your wet arm - put them in awe of your 'physics magic' ~patty

Patricia Rourke Patricia Rourke 45925 Points

finally - the cup and washer demo - it can be found here or use my words materials: 1 styrofoam coffee cup - 8 oz size two small circular washers 2 elastic bands metal paper clip small pieces of masking tape Knot two elastic bands together to make one longer elastic band Knot each end around a small steel washer and tape the ends to the washer Poke a small hole in the center of the bottom of the cup with a pencil Push the elastic bands through the hole from the inside Attach a paperclip to the elastic bands on the outside of the bottom of the cup to hold them in place Hang the washers over the lip of the cup - there should be sufficient tension in the bands to hold the washers in place but not to flip them into the cup Ask students to predict what will happen if you or they (let them make their own) drop the cup with the bottom facing the floor from a height of about 2 meters As the cup and the washers are in free fall together, the elastic bands pull the washers into the cup. Enjoy and let us know if you do any of these simple demos. ~ patty


Eric Roth Eric Roth 3375 Points

Patty, Great demo ideas. Thanks.

Adah Stock Adah Stock 101510 Points

Alexander: I had an experience at the Ben Franklin Museum of Science so many years ago that I can't tell you. However, I use that experience by retelling it to students and activing it out with current students. At the museum there was (and probably still is) a room full of scales and each scale had the name of a planet on it. At that time Pluto was considered a planet. I entered that room and stepped on the scale that read earth and I weighed 100 pounds. I stepped on the scale for Jupiter and I weighed 300 pounds. I stepped on the scale for the moon and I weight about 20 pounds. I was very upset and didn't know the difference between weight and mass. I was so upset I went to the guard at the room's entrance and told him his scales were broken. He laughed and said they weren't broken. After telling this story I ask for a volunteer. I tell the kids that the front of the room is a scalle for Earth. At the back of the room is a scale for the moon. At the right side of the room is a scale for Mars, and on the left side of the room is a scale for Jupiter. I grab the hand of the volunteer and tell the class that he or she and I are going on a trip to space. Before that I weigh the girl (imaginary weighing). I mention that she is also 100 pounds. I grab her hand and we go to the right and pretend to weigh her and she weighs about the same. I then grab her hand and we go to the moon. I tell her to get on the scale and her imaginary weight is 20 lbs. I repeat this again and go to the right again (now the left side of the room) and she steps on the imaginary scale and weighs about 300 pounds. We then travel back to earth and she steps on the imaginary scale and she weighs 100 pounds again. I ask the students, what has changed as we moved from location to location. They can tell me weight. What hasn't changed and they say she hasn't changed. I ask if she lost weight on the moon because she weighed less? Did she loose an arm or a leg or something? They say no. So I ask again why. At that point I review the definition for weight and mass. Then they can say her mass didn't change. We go into why the weight changes and I explain that the mass of the planets change therefore the gravity changes accordingly. Finally I point out that there is no such thing as weightlessness. I point out that the astronauts on the space ship experience something called near zero gravity. There are wonderful sites like How Things Work that have videos to show kids about astronauts in space. Peerhaps that will help them understand what gravity does and how it can change. The kids like my personal experience and they like the drama in the classroom and after grabbing their attention I go to the hard facts. Good luck to you. Adah

Ronaldo Relador Ronaldo Relador 45295 Points

I was actually just fascinated reading all the creative ways of teaching in this thread. I really thank everyone for sharing.

Daniel Carroll Dan Carroll 18570 Points

I especially like the bottle with the hole. It is after all the action of orbiting the earth that makes them "weightless" they are in a constant state of free-fall.

Nicole Dainty Nicole Dainty 4100 Points

A lot of kids have heard the term "zero gravity" used, which can be quite misleading. To address this I just recently used a Probe by Page Keeley called "Talking About Gravity" by Page Keeley to start a discussion. (You can download it free here on the Learning Center). I asked students about the term zero gravity, and in what situation you'd actually be able to use it. Then, introduced the term microgravity. After students shared their reasoning, we watched short video clips from NASA: What is Microgravity: The role of Microgravity: Then we did an activity - also from NASA - to help understand the idea of microgravity. The kids liked this one a lot! (I teach middle school, by the way.)

Matt Bobrowsky Matthew Bobrowsky 6160 Points

I find nothing misleading about "zero gravity." If you are in free fall, you experience zero gravity. The dropped leaking water bottle is a great demonstration of this.

Jason Ward Jason Ward 1010 Points

Einstein came up with some great "mind experiments" that the students really enjoy. imagine you are in space in an elevator with no windows. Would you we able to tell whether you you were in motion or standing still? This gets kids to begin thinking about relativity of motion.

Patricia Rourke Patricia Rourke 45925 Points

Great start to another thread, Jason, that of relative motion. Often, I would ask students sitting on their seats to describe how they were moving on small white boards. As the students flashed their answers, I would separate out those who said not moving vs. moving in a circle or orbit and then start the students talking with each other. Then apply something like your thought experiment by having the students describe how they are moving with respect to a special camera in space that moves right in step with them, and one that is stationary. Nice foundations may be built for future discussions about forces and motion. Thanks so much for leading us here.

Natalie Hepting Natalie Hepting 610 Points

Hi Alexander, I am not sure if my resource will help you much with demonstration of weightlessness.But, I found a great story called "How to survive in Space" It is in a book with the following ISBN 9780545016285. The book is called "Boys book How to be best at Everything" I would suggest to use it with upper elementary. The boys in my class loved reading it.It talked about all the things that astronauts have to do, and how everything floats away. It describes real life "earthly" scenarios such as showering, eating, sleeping, brushing teeth, sitting on a chair in space. It also tell you how it is done in space (Nature of the "How to" title). Natalie

Patricia Rourke Patricia Rourke 45925 Points

Hi Natalie, Welcome and thanks so much for the post and the mention of another resource. If I may, I want to play the advocate here and ask if you also teach girls or are in a boys-only classroom? If girls are present, do you have a similar resource that emphasizes women in space and science? Thanks for sharing. We appreciate your voice and look forward to hearing it more. ~patty

Natalie Hepting Natalie Hepting 610 Points

Patty, you are making a good point. I am in special education and there have been times where the class only included boys. I also think why my boys were so interested in it is due to the nature of the title of the book. However, the article (story) is not written to only appeal to boys. In fact, it does not address any gender in specific. If you have a mixed gender class, I would simply copy out that story, and not even mention the book. There is a girl version available as well. I do not have a copy of the girl book, so I don't know if it has anything on women in space in it. Hope that helps. I definitely think that the story would appeal to any gender, I just happen to have boys only in my resource class at that time. Natalie

Patricia Rourke Patricia Rourke 45925 Points

Thanks for your reply, Natalie, and for clarifying the nature of the class and of the story. Making the story available without the title sounds like the thing to do in a mixed gender class, especially not to put the girls outside of the picture. Good suggestion. Patty

Patricia Rourke Patricia Rourke 45925 Points

I am glad that you are finding resources that are useful and perhaps exciting for you. Have a great time adapting them to your classes. Patty

Diana Jeff Diana Jeff 20 Points

What an excellent demonstrations over here. I've never seen such a beauty in science to show how gravity still affects objects in space even though they appear weightless. I am glad to be here as you are showing your fine skills, resources that are so useful to all the teachers & members of this forum. I appreciate your pedagogy !! Diana Jeff

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