Bottle Blaster

Physics:	Air Pressure, Vacuums
Grade Range:	High School
Format:	Stage

This demonstration is an exciting way to show students how strong air pressure can be. Be sure to have a trash can nearby to collect the pieces of the bottle after presenting. This demonstration requires a lot of practice before performing.

Materials

• Empty Glass Bottle
• Water
• A Large Tub
• Optional: A Rubber Mallet

Safety Precautions

Please read the Physical Demonstration section of the Demonstration Safety page before performing this demonstration.

This demonstration requires: Safety Goggles

Demonstration

1. Fill the bottle most of the way with water, leaving a small amount of air space at the top. Let the audience know that you are going to be breaking off the bottom of the bottle without touching the bottom. Feel free to ham it up (claim that you are using the force, magic, etc.) or to claim your rubber mallet has special powers.
2. Place out the tub or similar underneath you and the bottle. Hold the bottle in front of you, with your non-dominant hand gripping it around the neck, and the mouth of the bottle fully visible. Be sure the bottle is held low, around waist height.
3. If using your hand, strike the mouth of the bottle with your dominant hand, striking it downward with the palm of your hand. Be sure to cover the entire mouth of the bottle when you do so, and to allow the bottle to slide in your non-dominant hand. It may take a few attempts, But when you hit it correctly the bottom of the bottle will fly off, spilling water everywhere!
   1. If using the rubber mallet, be sure to strike the mouth of the bottle evenly with the mallet head, fully covering the mouth of the bottle. When done correctly, the bottom of the bottle will fly off, spilling water everywhere!
4. Ask the audience for ideas on why this happened. Do you really have special powers? What is the secret to this demonstration?

Why This Works

Pressure is when a force is applied over an area. Air pressure refers to the force that the air exerts on everything around it. We can increase the pressure on something by either increasing the force applied or decreasing the area it is applied to. With this demonstration, we are increasing the pressure applied to the air and water inside the bottle. When the presenter smacks the bottle, they are forcing a small amount of air into the bottle, which increases the pressure inside the bottle. The air, when it experiences the increase in pressure, tries to balance it out by compressing, or taking up less space in the bottle. The bottle is also sliding in your grip, which forces the air in the bottle to compress even more. Water, however, does not compress, so the extra space that the air leaves is taken up by the water. This creates a small vacuum in the bottom of the bottle, a literally empty space with nothing in it, just like outer space! The vacuum collapses when the air expands back, pushing the water down into it. This "water hammer" smacks down hard onto the glass, breaking it off!

Additional Information

• The size and shape of the bottle will affect the quality of the demonstration. A bottle with a small mouth and a wide base works better than one with a mouth similar in size to the base.
• The amount of water in the bottle will affect how easily you can break it. You want your bottle to be between 2/3 and 4/5 filled with water.
• Check out this video by Youtuber Mark Rober on figuring out how this demo works!
• This demonstration pairs well with the Marshmallow Smashies and the Crush The Can demonstrations.
• This demonstration can be a part of the Pressure Show.