Marshmallow canon- a sweet projectile. How to make and set up the demonstration with Simon Taylor

The marshmallow canon is a projectile machine that propels marshmallows or small objects, it can easily be built out of PVC pipe and requires a household vacuum cleaner for its engine. The marshmallow is the fired projectile and gets sucked out of the barrel of the canon.
What you need:
• A length of 100cm of PVC pipe (32mm diameter).
• Two types of joiners- 3 way and double ended.
• Sellotape and a small piece of plastic-the flap.
• A vacuum cleaner.
• A bag of marshmallows.
• A retort stand, clamp or a chair
Exploring
Using a 100cm length of PVC pipe which can be purchased from most hardware stores, cut the main barrel of the canon with a hacksaw to a length of 85cm. The short tube left over needs to be of 9-10cm in length. Slot the 3-way joiner over one end of the 85cm length, and either use glue or sellotape to stick the joiner on. Then slot the short 9-10cm tube into this and add the double joiner. At this end of the barrel, using sellotape stick a small piece of flexible plastic, such as a plastic bag or cellophane, to make a hinged flap-this creates the suction in the barrel and sucks the marshmallow along the barrel and out. (See figure). Connect the vacuum cleaner to the end of the double joiner and turn on. Load the marshmallows at the opposite end of the tube and watch them fire out as perfect projectiles!
Science ideas
A projectile is any object that moves through the air without its own source of power, only under the influence of gravity (e.g. Bullets, rugby balls, shot puts, water jets and flying marshmallows!). Another important force that acts on all projectiles is air resistance. This force is not constant, because its size changes with the speed of the projectile. The position and acceleration of a projectile at equal time intervals shows the path travelled is the shape of a upside down parabola.
Further exploration
• Try one marshmallow at a time, then load 2-3 consecutively and see what happens.
• Change the height of the cannon by raising the angle and notice the difference of height and range to the marshmallow flight.
• Try other types of projectiles such as paper rolled up as a ball or build a small rocket or plane that could be loaded into the tube.
• Try building a canon with a longer barrel and explore the difference of the projectile motion.
• Record a video of the projectile in slow time, calculate speed and time of flight.