Arclind Mindspace is a free self-learning platform with simple crash courses and collective mind sparks for independent learners and creators.

Mindspace's goal is to simplify learning with lessons in just 3000 characters and sparks of insights in 1500 characters.

Self-paced. Community-driven. Free forever.

The longest vertical straw you can drink from is 10.3 metres. Even if you use a vacuum pump it won’t suck the liquid higher than that! Here is why!

Contrary to your intuition, when you drink from a straw you are not actually sucking up the fluid here. Just the air. So, when you do that, inside the straw, the pressure drops lower than that of the atmospheric pressure (101 kPa) outside. So, it’s the outside air pressure that pushes the water into the straw.

As the liquid moves up the straw, it is fighting against the gravity that is pulling it downwards. But it still keeps rising as long as the atmospheric pressure is greater than the pressure inside the straw due to gravity (weight of the liquid column).

The more liquid enters the column, the more it weighs. And at a certain height, there’d be enough water in the straw that’d exert the same pressure as that of the atmospheric pressure. That height, at sea level on earth, for water is 10.3 m.

$$ p_{atm}= 101\;kPa $$

$$p_{straw}= \dfrac{F}{A} \Rightarrow \rho g h$$

$$\rho g h = 101 \times 10^3\;N/m^2$$

$$h = \dfrac{101 \times 10^3\;N/m^2}{10^3\;kg/m^3 \times 9.81\;m/s^2}$$

$$h = 10.3\; m$$

Playful aggression or cuteness aggression is the term for when one experiences an aggressive response to an adorable stimulus like a baby’s cheeks or a fluffy unicorn toy. The response is a harmless urge to pinch and squeeze a baby’s face. People would say something like “You’re so cute and I am going to eat you up!” in an aggressive manner, gritting their teeth or clenching their fists, but in a harmless and tender way.

This is similar to a stimulus of intense happiness evoking an accompanied negative emotion like crying to keep the hormones balanced.

In 1841, near West Roxbury, Massachusetts, there was a socialist utopian experiment led by George Ripley at a two hundred acre estate. Based on the principles inspired by Charles Fourier, educated men and women participated and carried out a shared communal life and labour, building a Phalanstère (a self-contained utopian building). But in March 1846, the building caught fire. Starting with a severe financial setback, the experiment eventually failed.

All user contributions are licensed under CC BY-NC-SA 4.0

Explore All Sparks

Free Education. For All.
Educate the world. Share your knowledge.