When helium filled balloons are handed out at public events, they usually come with a piece of string or ribbon attached. The attachment is either tied into the knot, or secured with a plastic disk.

When you accelerate in a car, the seat you are sat in pushes you forwards, with the result that you feel like you are being ...

Bring the candle under the helium balloon until the tip of the flame touches the balloon. Be prepared for an explosion. Do not light the string on fire! Repeat with the hydrogen balloon. The explosion ...