How have sea levels changed over time? Over the last 542 million years they have varied from 130 m lower than their level today to a theoretical 300 m higher than they are today. It is theoretical because the continents move around a lot, and it is difficult to find evidence for where the seas […]
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How much height does a parachute need? It completely depends on the type of parachute. We need to think about how long it takes a packed parachute to be released and inflate. Parachutes are packed into the backpack they are carried in and they are usually made of nylon these days. They used to be
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Is a force field possible? In theory, there are several possibilities, such as warping space time, electric fields, directional lasers, a controllable plasma, a magnetic field, and others. We have all seen science fiction movies where a spaceship is protected by a forcefield that destroys enemy fire when it comes into contact. The recent movie
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Why do we have capital letters? Because the majority of the letters in the alphabet we use came from Latin. This question is actually the wrong way round. It should be asking why we have lowercase letters. The majority of our writing these days is done in lowercase with the occasional capital letter thrown in,
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Why are bridges designed to move? Because they expand and contract, because the wind moves them, and because the land on either side of them moves. When you drive on and off a bridge, you may have noticed there is a slight gap at either end. This gap usually has a metal bracket on it
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How does a helicopter with two rotors work? The rotors rotate in opposite directions and are on a transmission so that they don’t collide with each other There are over twenty different types of helicopter that have two rotors. The Chinook is probably the most famous. It was invented in 1961, but the first tandem-rotor
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Why does a boomerang come back? One wing travels faster than the other which causes it to fly in a circular path. However, not all boomerangs are designed to come back and the one most people are probably thinking of is the modern version of the boomerang. The boomerang was a weapon used by the
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What are rare earth metals? They are a group of 17 elements on the periodic table that are spread out so much in the earth that they are difficult to mine, hence the name “rare”. There are seventeen rare earth elements, and they all have different uses. Here they are with their uses: Yttrium –
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Why aren’t there flying boats anymore? Because landing and takeoff is rough, they are not very stable, engines became more powerful, more runways on land were built, and the sea is very corrosive. Before we start, let’s have a quick look at what a flying boat actually is. You are probably thinking of one of
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Why do British people say football and Americans say soccer? Britain used to call football soccer until about 1980 when they started to call it football. Before we start, this article is about the sport of two teams of eleven people trying to kick a ball into each other’s goal. Not the sport that is
#695 Why do British people say football and Americans say soccer? Read More »
