Solar Tube

SKU #SLR-222

(19 reviews)

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Watch as this 60' solar tube gently lifts into the air.

Description

Watch this amazing tube gently lift into the air. At 60 feet long with a 72 inch circumference, this is the largest Solar Tube available. Run to fill with cool air, tie off the end, and move it into the sun. As the bag heats, the 240 cubic feet of air expands, becomes less dense, and floats. A great demo of density, thermodynamics, solar energy and more. Hold onto the string! Our Solar Tube is made from thin plastic in order to float; use care when handling for best results. Includes tube, string, and instructions.

Read more on our Blog - Density of Gasses

Lesson Ideas

Download the pdf of this lesson!

A black plastic tube is filled with air, sealed, and tethered. After a few minutes, the tube slowly rises into the air.

What Does It Teach?

Hot air is less dense than cool air.
Black objects absorb heat faster than the lighter colored surroundings.
Gases expand when heated.
Volume and temperature are directly related. As one increases, the other increases.
Archimedes' Principle and Buoyancy

Procedure:

On a cool but sunny, non-windy day, determine the mass of the Solar Tube.
Bring your class outside with the Solar Tube, a roll of kite string, scissors, a meter stick, and a roll of 2-inch cellophane packing tape.
Unroll the Solar Tube in the shade, away from trees and bushes to avoid tears, and measure its flat dimensions.
Open the Solar Tube and run to fill it with the cool air near the ground*. Tie off the open end. If the Solar Tube should tear, use a small amount of packing tape to repair the hole.
*Alternatively on hot days, use a fan to fill the tube with air from inside, then bring the filled tube outside.
Tie kite string to the tied off end of the Solar Tube, move it into direct sunlight, and hold the other end of the kite string.
Observe the Solar Tube becoming rigid as the air inside expands with the absorbed heat from the sun. Just before lift-off, measure the temperature of the surrounding air and the Solar Tube's temperature. (Note: The Educational Innovations Infra-Red Thermometer, IR-100 is perfect for this.)
When finished, reel in the Solar Tube, cut off the knot, and roll up the Tube so that it can be used again.

Warning: Do not release the Solar Tube into the air. At higher altitudes it would become an aviation hazard!

Explanation:
Why do some objects float and others sink?

Archimedes discovered that an object is buoyed upward with a force equal to the weight of the fluid displaced. An object displaces or takes the place of an equal volume of fluid: air, water, milk, etc. An object will float in a fluid whenever its mass is less than the mass of the fluid displaced; otherwise, it will sink. For example:

Consider a large, helium filled balloon with a volume of 24.5 liters and a mass of 14 grams. The displaced 24.5 liters of air has a mass of 30 grams. Since the mass of the balloon is less than the mass of the air displaced, the balloon will float.
Consider a piece of aluminum metal with a volume of 10.0 cm³ and a mass of 27.0 grams. The displaced 10.0 cm³ of water has a mass of 10.0 grams. Since the mass of the aluminum is more than the mass of the water displaced, the aluminum will sink.

Why does the Solar Tube initially sink and then float in air?

At first, the Tube containing the cool air weighs more than the air displaced. It sinks to the ground.
Inside Air + Tube = 1000 g -- Displaced Air = 500 g
As the black Tube absorbs heat from the sun, the air inside expands, displacing more outside air. When the mass of the Tube with warm air displaces an equal mass of outside cool air, the Tube starts to float.
Inside Air + Tube = 1000 g -- Displaced Air = 1000 g
As the Tube increases in temperature, it expands, displacing more outside air. It then lifts off into the air.
Inside Air + Tube = 1000 g -- Displaced Air = 1500 g

Data:
Mass of the empty rolled Tube: _______
Width of the flat Tube: _______
Length of the flat Tube: _______
Outside air temperature: _______
Tube temperature at lift-off: _______

Calculations:

Consider the completely inflated tube a cylinder. Calculate its volume.
Use the Tube lift-off temperature and the air ground temperature to calculate the percent the Solar Tube was initially filled with air.
Use the answer to question #1 along with the density of air at 25^o to be 1.2 g/L to calculate the mass of air inside the Solar Tube at lift off.
How does the mass of displaced air compare to the filled Solar Tube:
1. Initially
2. At lift off, and
3. Floating in the air.

Challenge Questions:

The angle that the tethered string makes with the ground is a function of wind speed and temperature difference. Can you quantify this?
The amount of lift of the Solar Tube is a function of the difference in temperature between the cooler external temperature of the surroundings and the warmer internal temperature of the Tube. Can you quantify this?
What is the minimum Solar Tube temperature to allow the Tube to rise when the ground temperature is: 20^oC? 25^oC? 30^oC?
How does a change in the external temperature affect the buoyancy? Educational

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Reviews

19 reviews

Amazing

Feb 5, 2020

I teach high school physics, and this is one of the best demonstrations I've seen! The kids are in awe when it lifts into the air! Since it needs to be light enough to float, the plastic is thin and care has to be taken not to rip the bag. If I could give it 6 stars I would!!!

James F.

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Not proof against external ignorance

Apr 29, 2017

Easy to fill with air. Works well. But don't forget to wise up the neighbours. Some little boys pelted rocks at the tube and punctured it massively twice, both missiles entering one side and coming out the other.

Alfred Bhulai

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Science Magic class

Jul 3, 2015

Students were awed with the ease of filling the solar tube with air. They enjoyed the lift off during both classes! Adults were snapping pics as they couldn't believe the size being lifted so easily.

Pat Smith

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too big to handle alone

Oct 16, 2014

This thing is huge! It can be a bit unwieldy and you need a blower to inflate it (we used a shop vac). Wind is definitely a factor.You need a whole lot of room and a couple adults to make this work.

Paula

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Students loved it

May 15, 2014

My students love this solar tube. We did have a problem with the string - it was a bit of a windy day and the string broke. The tube took off and rose high in the sky traveling in a general northeast direction. I hope we did not cause any concern for air traffic in the area. I will buy stronger string or not use it on a windy day next time.

Robin Buff

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CEO

Apr 14, 2014

Love the size of the solar bag but string broke twice. Was a little scary since we did not want this 60 ft. bag to float away.

Atomz Lab

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Way cheaper!

Jun 9, 2013

Way cheaper than other science sites. Thank you!!!

Lynn

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Solar Tube

Oct 3, 2012

The Solar Tube worked as suggested but would recommend experimentation to take place in the afternoon and not in the morning as suggested. We used the tube multiple times but did run in to issues with tears. Neat experiment though and the kids enjoyed it. A good experiment to depict a more difficult concept.

Ace Filipp

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Solar Tube Sums Up Physical Science!

May 29, 2012

What a great way to end a year of Physical Science! This super fun rising tube ties together so many concepts studied throughout our 8th grade year - molecular motion, thermodynamics, density, absorption of light/heat (have a white garbage bag for comparison), competing forces, polymers, mass and volume calculations, Bernoulli's Principle (when filling), etc. Not many inexpensive class items can facilitate this much student engagement! Bonus feature: younger students who see you use the Solar Tube with your classes will find you very cool and will want to be in your class next year.

Maureen Horne

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Great fun

May 29, 2012

I use these on mole day. My students present projects during lunch and between lunch we have an hour to kill and this is always fun and educational. The kids never think it will actually float and then we can take great class photos under it.

Jamie Flint

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Great Product

May 29, 2012

Love this item. Can be used over and over. Just as fascinating for adults as it is for kids!

Jacqueline Sipples

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Does Hot air go up?

May 29, 2012

Most people think that hot air goes up, well it doesn't! Warmer air goes up. The Solar Bag goes up when the air inside heats up and is warmer than the air around it making it less dense. I have used Solar Bags for years in teacher workshops, science show for every grade level all over the country. Children as well as adults are always amazed as they help launch this giant tube lift off the ground and fly into the air.

Ben Roy

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Solar hot air balloon

May 22, 2012

I bought 5 of these last year to use with 4th graders at an environmental field day, and ordered the same this year. Last year, it worked well, and the students learned a great deal and had fun. There was one problem. The thin kite string holding one of the balloons broke, and the balloon escaped. When last seen, it was headed east to JFK Airport. We called the police to alert them, and there were no further problems, but this year, I'm using stronger string.

Judy Famellette

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Great Advertising!

May 22, 2012

Our 4-H group took a couple of these to an event downtown at the park. We put huge 4-H clovers on the ends and the kids and parents loved it. Was a great way to share a science activity as well as get some exercise and recruit for 4-H.

Angela

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cool tube!

May 22, 2012

I never thought that so many kids would be interested in this solar tube. After I got it out to show my 5th grade class, within 5 minutes, I had what seemed like half the school around me. Even 11th graders came over to help and see what was going on. What a great way to get kids excited about science.

Kurt

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Solar Tube

May 17, 2012

The solar tube is an awesome demonstration to do for elementary age students. Actually, students and adults of all ages enjoy seeing it launch. The students learned sbout heat transfer and energy and it went along with our study of airplanes and rockets.

Becky Dimino

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Fantastic

May 16, 2012

I used the Solar Tube on a sunny day, the day before vacation. My students had a wonderful time trying to get a little air inside and watching it rise. I used it for five classes and needed to patch holes with tape - but that added to the adventure. Not only did we have a wonderful class, but I can still refer to the experience to remind students about a range of relative concepts.

Raquel

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Giant Solar Tube

May 16, 2012

Great mind-boggling size and demonstration but too easily torn by children and the outdoor environment it's used in.

Kaylyn Mabey

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Great demo of solar energy

May 16, 2012

The students had great fun running to get the air into the bag. Once filled make sure you have a GOOD hold on the bag since it begins "lift off" in seconds IF it is sunny. The process will take longer if cloudy. This is a great demo of how solar energy heats air and results in that air expanding. This is a visual that will be remembered for a long time. Downsides: 1) if you tie this off with a string and then allow the "string" to hold the balloon as it floats be careful since the string may break and the balloon could easily float away, 2) I had students roll up the balloon for storage and it collected, by static electricity, small pieces of dirt and artificial turf (they had been on the soccer field flying the balloons). Worth the money.

Mary Haskins

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NGSS

This product will support your students' understanding of the Next Generation Science Standards (NGSS)*, as shown in the table below.

Elementary

Middle School

High School

1-PS4-3

Students can use the Solar Tube to plan and conduct an investigation to determine the effect of placing objects made with different materials in the path of a beam of light.

4-PS3-4

Students can use the Solar Tube to design, test, and refine a device that converts energy from one form to another.

3-5-ETS1-3

Students can use the Solar Tube to plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved.

MS-PS4-2

Students can use this tool to develop and use a model to describe how waves are reflected, absorbed, or transmitted through various materials.

MS-PS3-3

Students can use the Solar Tube to apply scientific principles to design, construct, and test a device that either minimizes or maximizes thermal energy transfer.

MS-ETS1-4

Students can use the Solar Tube to develop a model or experiment to generate data for iterative testing and modification of a proposed object, tool or process such that an optimal design can be achieved.

HS-PS4-5

Students can use the Solar Tube to conduct investigations about technological devices use the principles of wave behavior and wave interactions with matter to transmit and capture energy.

HS-PS3-4

Students can use the Solar Tube to design, build, and refine a device that works within given constraints to convert one form of energy into another form of energy.

HS-ETS1-2

Students can use the Solar Tube in an investigation to design a solution to a complex real-world problem by breaking it down into smaller, more manageable problems that can be solved through engineering.

Suggested Science Idea(s)

3-5-ETS1-3
4-PS3-4
MS-PS3-3
MS-ETS1-4
HS-ETS1-2
HS-PS3-4

Given a sunny day and the Solar Tube, students are treated to a simple device that converts light energy into heat energy.

1-PS4-3
MS-PS4-2

On a sunny day, allow students to create their own Solar Tubes using a variety of materials to investigate how the light energy conversion is improved or halted.

HS-PS4-5

Given a sunny day and the Solar Tube, students can make a practical connection between principles of wave behavior and wave interaction with matter.

* NGSS is a registered trademark of Achieve. Neither Achieve nor the lead states and partners that developed the Next Generation Science Standards were involved in the production of, and do not endorse, this product.

Solar Tube

NGSS

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