• Balloon
• Chairs -2
• Paper towel or toilet paper roll
• String (3.5 m)
• Packing tape

1. Thread the string through the paper towel or toilet paper roll.
2. Attach the string to two chairs, about 3 m apart, such that the string is tight.
3. Stand behind one chair. Make sure that the paper towel roll is touching the chair.
4. Take a length of packing tape (approximately 30 cm) and make a loop, so that the sticky side faces out.
5. Attach this loop of tape to the top of the roll or tube.
6. Blow up a balloon as much as you can, and then attach the balloon horizontally to the tape on the toilet paper roll. The mouth of the balloon should be facing you.

• Try this activity with different sized balloons and differing amounts of air.
• Try different types of string. What type offers the least resistance to the balloons motion?
• Try this with the string tied to chairs with different heights- does adding a slope make a difference?
• Make it into a race! In teams, see how fast each team's balloon makes it to the other side of the string.
  

When the balloon is released, the air pushes out the bottom of the balloon. The air is faster moving than the air in the space surrounding the balloon. Bernoulli’s Principle states that faster moving air has lower pressure, so by releasing the balloon, we have created an area of low pressure. Air molecules like low pressure areas so they move towards this area and push the balloon forward along the string.

Also, in order for an object to move, the energy used to move it must overcome the friction between the object and the surface it’s resting on. The balloon must overcome the mass of the tube it is attached to and the friction of the string. The larger and heavier the tube, the greater the friction.