# Why does the shower curtain stick to you?

There’s nothing better than cooling off with cool showers in the bathroom on hot days, except for the annoying curtain that clings to you when you get out of the shower. Why does this always happen?

The answer to this phenomenon belongs in the realm of physics.

“Since a curtain is large but light, they work with the small vacuum created in the bathroom ,” explains Ohle Claussen of the Max Planck Institute for Motivation and Self-Organization. There will be at least two physical effects that lead to this phenomenon occurring when you shower.

You can easily create a similar vacuum yourself by taking a thin piece of paper or receipt and holding it to the edge of your lower lip. If you blow hard, the piece of paper will not be pressed down, but on the contrary, will curl up. You can see this phenomenon in the image below.

If you blow hard, the piece of paper will not be pressed down, but on the contrary, will curl up.

What happens in the above experiment is called the Bernoulli effect , which is part of the reason why airplanes can fly. Mathematician Daniel Bernoulli describes that in a space where the velocity of the fluid is higher than that of its surroundings, at the same time the air pressure there will always be lower than that of the surroundings.

So if you blow hard on the paper, the air velocity at the top will be higher than the bottom of the paper because most of the air underneath is only moving very slightly. This reduces the pressure of the air above the paper, creating a vacuum that draws the paper upwards. The phenomenon of the “friendly” shower curtain also originates here.

“As air enters an area of higher fluid velocity, it must accelerate to accommodate this velocity. In fluid mechanics, such acceleration is combined with a pressure drop to form The additional kinetic energy the air particles receive is due to the high air pressure in the region of the slow fluid, which acts on these air particles as they reach the region of the faster fluid. “ , Claussen explained.

So pressure and speed are always related where air flow occurs. The place with the highest speed is also always the place with the lowest pressure. “So if your shower head sprays water at high speed in the bathroom, the air in it will be carried away. As a result, the air from outside has to get into the shower and accelerate, resulting in a reduction. pressure” , according to Claussen.

David Schmidt, a scientist from Massachusetts, highlighted the second cause of pressure drop, relying on computer simulations of the motion of water droplets. It shows that the sprayed shower droplets create a vortex, which also contributes to a decrease in pressure in the air.

Shower curtains will act with the small vacuum created in the bathroom, causing them to stick to us.

This effect is just as amazing as the Bernoulli effect, according to Claussen. This discovery made in 2001, shows that even a small impact because the large but light curtain can be separated from you even under the slightest pressure.

The closer the air brings the curtain closer to the body, the stronger the Bernoulli effect is: The same amount of air must flow through a smaller opening and therefore must circulate even faster in that small area. This reduces the pressure at the approach point until impact occurs.

So try attaching some heavy objects under the curtain, threading a lead wire into its hem or sticking the curtain to the tub with water !