With this month’s Let’s Discover!, you will build a solar-powered airship to harness the blistering heat of the summer sun. You only need a few things for this experiment: three black (or dark-green) plastic garbage bags, scissors, tape and preferably some fine thread or fishing line.
Hot air balloons operate on the principle that warmer air rises over cooler air; if you heat the air inside a big bag (a balloon), it will rise above the surrounding cooler air. Hot air balloons generally use a large propane burner to heat their air, but you don’t need anything that fancy. With some dark plastic bags, you can absorb enough heat to make something fly!
You will need to combine three (or more – experiment!) bags together to get a good-sized balloon. Cut the ends off two bags so that they are now dark plastic tubes, and connect the three pieces together with tape. It is important to make sure that there aren’t any holes in your bags or seams, so that air cannot escape. You should also have one remaining open end, and before you seal the whole balloon shut, shake the balloon through the air to slightly inflate it – this will ensure there is enough air inside.
To launch your balloon tape or tie a string to your balloon (otherwise your balloon may escape), and leave it in the sun. As the sun’s rays strike the dark plastic, they’ll be absorbed and converted into heat. Your balloon’s air will heat up, expanding and stretching out your balloon, and eventually beginning to rise off of the ground. For extra fun, attach weights to your balloon to see just how much it can lift! (Pro tip: you will lift the most when the balloon weighs as little as possible; unlike with your garbage, you want the thinnest possible bags for your hot air balloon.)
While Nova Scotia’s summers can get wonderfully hot, don’t forget that Discovery Centre is air-conditioned. If the parks and back yards are too hot to handle, come cool off your body and warm up your brain on Barrington Street!
For more great things to discover – visit the Discovery Centre on Barrington Street in Halifax, check out their website or join them on facebook