I learned this today. Steam cars outnumbered internal combustion engine cars and electric cars from 1900 until about 1907. Steam engines are external combustion engines because the fuel is burned away from the engine. They release far fewer polluting gases than internal combustion engines. A steam engine works by burning a fuel source to heat […]
#78 Why were steam cars so popular in 1900? Read More »
I learned this today. When dogs were domesticated, their temperaments changed, their skulls, teeth, and paws shrank, their ears flopped, they became docile, their coats changed color, and they learned to read human expressions. Nobody really knows where dogs were first domesticated. There is some evidence that it was in China over 30,000 years ago.
#77 How did dogs change when they were domesticated? Read More »
I learned this today. The first dinosaur was named 20 years before the word “dinosaur” was invented. Dinosaur fossils have probably been dug out of the ground ever since people have been able to dig, but no one would have known what they were. Chinese writings from about 2000 years ago reference dragon bones, which
#76 When were the first dinosaur bones found? Read More »
I learned this today. All of the black squares in a QR code represent certain pieces of information. QR stands for Quick Response. They were invented in 1994 by Masahiro Hara. He was working for the Japanese company Denso Wave and he got the idea by looking at the black and white pieces on a
#75 How does a QR code work? Read More »
I learned this today. Tectonic plates move because the weight of their cold dense side pulls them into the mantle of the Earth. This is called slab pull. Hot things rise and cold things sink. This occurs because hot things have more energy than cold things, so the atoms move more and spread out. This
#74 Why do tectonic plates move? 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. Whales can hold their breath for so long because they can store oxygen in their blood and muscles. On average, whales can hold their breath for about 60 minutes. The sperm whale can hold its breath for about 90 minutes and the Cuvier’s Beaked Whale can hold its breath for 138
#72 How can whales hold their breath for so long? Read More »
I learned this today. Jellyfish don’t have a brain. They also don’t have a stomach, lungs, or a heart. They just have two separate nervous systems. Jellyfish are not fish. They are the medusa-phase of certain gelatinous members of the subphylum Medusozoa. They are in the group of sea creatures called cnidaria. This also contains
#71 How do jellyfish survive without a brain? Read More »
I learned this today. There are different ways that animals can change their colors. Some of the ways take days and some of them take seconds. Let’s look at the slow way first. Some animals change their color very slowly. Some do it by completely shedding their fur. These are mostly mammals or birds that
#70 How do animals change color? 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 »
