Ingredients

n Mouth

n Hand

Science terms

n Air Pressure – Air pressure is the force that air puts on objects.

n Bernoulli’s Principle – Bernoulli’s Principle is the scientific principle that states that the faster a gas or liquid moves, the lower it’s pressure will be.

Instructions

n Step 1: Pucker your lips as if you are going to whistle and then force the air from your lungs out of your mouth to the back of your hand.

n Step 2: Open your mouth and then force the air from your lungs out of your mouth to the back of your hand.

Explanation

The air blowing out of your puckered lips feels cooler than the air blowing out of your wide open mouth. It’s all about the size of the opening of your mouth. As the air is forced through your puckered lips its speed increases. This causes the moisture on the back of your hand to evaporate more quickly. Evaporation is a cooling process. When your mouth is opened wide, the air is not moving as quickly. Therefore, as the air hits the back of your skin, less evaporation occurs, and the air feels warmer.