What happened to biplanes and triplanes? They produce too much drag, which means they can’t fly fast enough and they use a lot more fuel. The first planes built were biplanes. The first heavier-than-air plane was a triplane. Sir George Cayley built a glider with three wings in 1848. He managed to convince a local […]
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Why are there 12 signs of the Zodiac? Because the Babylonians decided that there should only be 12. What are the signs of the zodiac? The signs of the zodiac are the symbols that represent the 12 different constellations that the sun passes in front of throughout a year. They are all found in a
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How does C-4 work? It rapidly produces gases at an explosive velocity. C-4 is a plastic explosive called Composition C-4 and it is the fourth in the series. Composition C was discovered in World War II and the first type was only called Composition C. Each variation had problems that were ironed out by the
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Is Krav Maga effective? Yes, or the Israeli army wouldn’t teach it. However, you need to train in realistic situations. Krav Maga is a martial art that was created for the Israeli Defense Forces. The words krav maga are Hebrew. קרבנגע. Krav means “combat” or “battle” and maga means “contact” or “touch”. It was created
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What is the range of a cell phone tower? The average maximum range of a phone mast is about 40 km, 25 miles. How does a cell phone tower work? Cell towers have detectors and transmitters to receive and transmit radio signals. When you want to look at a website on your phone, my site
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How do you get water to the top of a skyscraper? Water is pumped up to a series of tanks at different heights. Early pumps were usually suction pumps and a suction pump cannot be used to get water to the top of a skyscraper. A suction pump cannot pump water to a height greater
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What is a hollow-point bullet? It is a bullet that expands on impact, causing more damage, without going all the way through the target. With a hollow-point bullet, the tip is literally hollowed out. A cartridge has four parts. It has the case, which holds everything together. It has the primer, which is struck by
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Why did early humans leave Africa? They were probably forced out by climate change, but they could have left because of their rising intelligence. Let’s look at the evidence for why paleontologists believe humans developed in Africa and then look at why they left. Humans probably separated from the common ancestor we share with other
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Why do soldiers break stride on a bridge? So that the vibrations don’t make the bridge collapse. This rule was introduced by the British Army in 1831. On 12th April 1831, the 60th Rifle Corps were returning from a military exercise and they crossed over the Broughton Suspension Bridge, which had been built five years
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How does a canal lock work? By using gravity to increase the amount of water in the canal and rise the boat. There are two different reasons why canals need locks. The first is that canals are bodies of running water and so they have an upstream and a downstream, giving them a current. They
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