Straws work just like your vacuum cleaner!?!

Sophia Xu
Updated: August. 30, 2023

Straws and vacuum cleaners may seem like very different objects, but they actually have a lot in common. Both of them use the principle of air pressure to create suction and move fluids or solids from one place to another.

How Straws Work

When you drink from a straw, you create a partial vacuum in your mouth by reducing the air pressure inside the straw. This causes the atmospheric pressure outside the straw to push the liquid up the straw and into your mouth. The greater the difference between the inside and outside air pressure, the stronger the suction force.

The equation for calculating the air pressure inside the straw is:

P = P_{0} - ρ g h

where $P$ is the air pressure inside the straw, $P_{0}$ is the atmospheric pressure, $ρ$ is the density of the liquid, $g$ is the gravitational acceleration, and $h$ is the height of the liquid column in the straw.

How Vacuum-Cleaners Work

A vacuum-cleaner works in a similar way, but instead of using your mouth, it uses an electric motor to spin a fan. The fan creates a low-pressure zone behind it, which draws air and dust from the nozzle into the vacuum-cleaner. The air and dust then pass through a filter or a bag, which traps the dust and lets the air out.

The equation for calculating the suction power of a vacuum-cleaner is:

S = \frac{Q Δ P}{P _{0}}

where $S$ is the suction power, $Q$ is the airflow rate, $Δ P$ is the pressure difference between the nozzle and the outlet, and $P_{0}$ is the atmospheric pressure.

Conclusion

Straws and vacuum-cleaners are both examples of how we can use air pressure to create suction and move fluids or solids. They are based on the same physical principle, but they differ in their design and application. Straws are simple and cheap devices that we use for drinking liquids, while vacuum-cleaners are complex and expensive machines that we use for cleaning surfaces. Both of them have advantages and disadvantages, depending on what we want to achieve.

I hope this blogpost helps you understand how straws are like your vacuum-cleaner. If you have any questions or feedback, please let me know. 😊

Search This Blog

Starlog :)