LITTLE ROCK, Ark. – Students in Arkansas will be continuing their education online and through AMI Days for the remainder of the 2019-2020 school year due to the COVID-19 pandemic.
This is a hard time for everyone, so the Arkansas Storm Team wants to do something to help! We will be providing a weekly weather education lesson, teaching students about a specific topic and showing how to create a fun science experiment at home.
This week’s lesson is all about the Bernoulli Principle! Before we get to the experiment, let’s cover some science about what the Bernoulli Principle is and how it works.
Bernoulli’s Principle states that an increase in the speed of a fluid (air) decreases the pressure of that air. A decrease in the speed of a fluid (air) increases the pressure of that air.
The faster air moves, the lower the pressure. The slower the speed of air, the higher the pressure.
Experiment 1 – Floating objects with a hair dryer
Items needed: hair dyer, ping pong ball or small inflatable ball (nothing too heavy).
Step 1: Turn the hair dryer on its cool setting, highest speed.
Step 2: Hold the ball in the flowing air and let go of it.
Step 3: Slowly tilt the hair dryer and see if the ball still stays in place, hovering.
Why doesn’t the ball fall over? High pressure and low pressure around the ball keep it floating in place.
Air coming out of the hair dryer is moving fast, it creates low pressure. Just underneath the ball, a small area of high pressure forms because the air slows to go around the ball. At the top of the ball, the air speeds back up, creating an area of low pressure.
High pressure always wants to flow to low pressure. So there is this upward motion taking place. Meanwhile, gravity is creating a downward force on the ball. Because of gravity counteracting the air flowing upwards, the ball stays afloat in the air.
What about when you tilt the hair dryer?
Slower moving air around the hair dryer creates high pressure. Again, high pressure always flows to low pressure. So the ball stays floating even when tilted (see video for better visualization).
The Bernoulli Principle explains how airplanes work. Air hits the wing and slows down trying to get over the wing, creating an area of high pressure. Underneath, the air flows fast without any interruption, creating a low pressure system. Equal balance on the plane helps the airplane stay up in the sky.
This is also how the weather works with high pressure and low pressure systems. Fast moving winds high in the atmosphere help create low pressure. Behind a low is a high pressure, chasing after the low.
Experiment 2 – Filling long bag with air.
Items needed: diaper bag or produce bag from grocery store
Step 1: Try blowing up the bag using just the air from your lungs. How did it work? Was the bag full or pretty empty?
Step 2: Now, using the concept of Bernoulli’s Principle – create a wide opening with your fingers.
Step 3: Using the air from your lungs (low pressure) plus the air around your mouth (high pressure), blow into the bag. The bag should fill up.
Experiment 3 – Balloon and/or paper blowing.
Items needed: two balloons or pieces of paper.
Step 1: Fill up the balloons with helium or just air from your lungs.
Step 2: Hold the balloons or pieces of paper apart.
Step 3: Blow fast air from your mouth.
What should they do? Will they move towards the center or away? Think about the Bernoulli’s Principle, high and low pressure.
Weather Fix Wednesday: Lesson 5 will be released on May 13, 2020 at 1 p.m. The topic will be albedo.