I learned this today. Quartz watches are far more precise than mechanical clocks because they make quartz crystals oscillate at a very precise frequency. A mechanical watch has an accuracy of ±5 seconds a day. Quartz watches have an accuracy of about ±5 seconds a month. For comparison, an atomic clock has an accuracy of […]
#83 How does a quartz watch work? Read More »
I learned this today. Our skin can allow sweat out, but it doesn’t let water in thanks to a thin layer of fat between the outermost layers of skin cells. The skin is said to be the largest organ in the human body. Actually, by surface area, it is the second largest because the inside
#82 Why is skin waterproof? Read More »
I learned this today. Dogs can probably smell cancer in people. Dogs have a phenomenal sense of smell. They have 300 million olfactory receptors in their noses. We have about 6 million. On top of this, the part of their brain that is devoted to analyzing smells is about 40 times larger than ours. It
#79 Can dogs smell cancer? Read More »
I learned this today. There are two ways of making electricity from solar panels. Directly, by using sunlight to make electricity, or indirectly, by using the sunlight to make heat. The sun releases energy in the form of photons. Photons are massless so they travel at the speed of light, 299,792,458 m/s. They travel from
#73 How do solar panels generate electricity? Read More »
I learned this today. Gyroscopes work because of the conservation of angular momentum. A gyroscope is useful to us when it is set in a gimbal because the axis of rotation on the gimble is free to assume any orientation, which means that the gyroscope at the center will move independently of the thing the
#69 How does a gyroscope work? Read More »
I learned this today. The difference between AC and DC current is that in DC the charge only flows in one direction but in AC it changes direction periodically. Direct current (DC) was first produced in 1800 by the Italian physicist Alessandro Volta. That is why the volt is named after him. He produced electricity
#64 What is the difference between alternating current (AC) and direct current (DC)? Read More »
I learned this today. We feel pain when we touch something very cold or very hot because of thermoreceptors in our skin that are activated by different proteins. Humans are able to withstand a fairly large range of temperatures, but we have to wear clothes to do this. Ancient humans started wearing clothes about 780,000
#63 Why do we feel pain when we touch cold or hot things? Read More »
I learned this today. The tallest a human could potentially grow is about 9 feet, 274cm. Humans grow because of a growth hormone called somatropin. It stimulates growth by telling cells to reproduce. It is released by the pituitary gland. It reacts with a specific receptor on the surface of cells, and it stimulates cell
#58 How tall could a human grow? Read More »
I learned this today. Spot welding was discovered by accident by Elihu Thomson in 1877 when he was giving a lecture on electricity and accidentally passed a current through two pieces of wire. Spot welding is obviously a form of welding. Welding is the process of joining any two pieces of metal together through heat.
#57 How does spot welding work and what is it used for? Read More »
I learned this today. Gold is so rare because it takes a staggeringly large amount of energy to produce it naturally. Gold has been treasured for as long as humans have been able to find it because of its unique properties. It is resistant to corrosion, conducts electricity and heat very well, doesn’t tarnish, is
#56 Why is gold so rare? Read More »
