ARBOR SCIENTIFIC P6-7300 Solar Bag Installation Guide
- June 11, 2024
- ARBOR SCIENTIFIC
Table of Contents
ARBOR SCIENTIFIC P6-7300 Solar Bag Installation Guide
Contents
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60′ long bag
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72″ Circumference
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Kite string
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Instructional Guide
Required for activity -
Meterstick (P1-1072)
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Infrared Thermometer (68-6510)
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Scissors
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2-inch roll cellophane packaging tape
Background
A black plastic bag is filled with air, sealed, and tethered. After a few minutes, the bag 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 Bag.
- Bring your class outside with the Solar Bag, kite string, scissors, a meter stick, and a roll of 2-inch cellophane packing tape.
- Unroll the Solar Bag in the shade, away from trees and bushes to avoid tears, and measure its flat dimensions.
- Open the Solar Bag and run to fill it with the cool air near the ground. Tie off the open end. If the Solar Bag should tear, use a small amount of packing tape to repair the hole. Alternatively, on hot days, use a fan to fill the bag with cool air from inside, and then bring the filled bag outside.
- Tie kite string to the tied-off end of the Solar Bag, move it into direct sunlight, and hold the other end of the kite string.
- Observe the Solar Bag becoming rigid as the air inside expands with the absorbed heat form the sun. Just before lift-off, measure the temperature of the surrounding air and the Solar Bag’s temperature.
- When finished, reel in the Solar Bag, cut off the knot, and roll up the bag so that it can be used again.
Warning: Do not release the solar bag into the air. At high altitudes it would become and 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 Bag initially sink and then float in the air?
- At first, the bag containing the cool air weighs more than the air displaced. It sinks to the ground.
- As the black bag absorbs heat from the sun, the air inside expands, displacing more outside air. When the mass of the bag with warm air displaces an equal mass of outside cool air, the bag starts to float.
- As the bag increases in temperature, it expands, displacing more outside air. It then lifts off into the air.
Activity
Data:
Mass of the empty rolled bag: ____
Width of the flat bag: ____
Length of the flat bag: ____
Outside temperature: ____
Bag temperature at lift-off: ____
Calculations: ____
- Consider the completely inflated bag a cylinder. Calculate its volume.
- Use the bag lift-off temperature and the air ground temperature to calculate the percent the Solar Bag was initially filled with air.
- Use the answer to questions #1 along with the density of air at 25o to be 1.2 g/L to calculate the mass of air inside the Solar Bag at lift off.
- How does the mass of displaced air compare to the filled Solar Bag:
a. Initially
b. At lift off, and
c. Floating in the air.
Related Products
Steel Sphere Density Kit (P1-1035) These two shiny, metal spheres have about the same mass, one has a diameter significantly smaller than the other, making their densities vastly different. Seeing the large one float in water seems unbelievable!
Density Rod Set (P1-1020) Use this discrepant event to test students’ understanding of density, buoyancy, and thermal expansion! The aluminum rod floats in cool water and sinks in warm. The PVC rod does the reverse and sinks in cool and floats…
Density Identification Set (P1-1110) Students identify each of 12 different samples by determining their density. Each cylinder varies in size (volume) and density, but has the same diameter of 1/2″.
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