熱気球は、内部の空気を暖めて外の空気より軽くし、その差が浮力となって浮上します。つなぎとめられた小型の気球内に温風を送って、温度差をみながらタイミングを図って切り離してみましょう。温度差と浮力の大きさの関係をみることができます。 The air in a hot-air balloon is warmer than the air outside of it, and lighter as a result. That makes the balloon rise up into the sky. In this exhibit you’ll blow warm air into a balloon, waiting for just the right moment to set the balloon free and send it floating up. Can you figure out the relationship between the heat of the air and the lifting power of the balloon?