Gravity is the fundamental mechanism that ensures the continuity of life on Earth and governs the motion of planets in our Solar System. Understanding its nature helps us to better grasp fundamental concepts such as speed, mass, orbit, and tides. Let’s take a look at some interesting facts about gravity:
Key Concepts
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Gravity and Mass: All objects that have mass attract each other. This mutual interaction is called the “force of gravity.”
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Orbits: Gravity keeps the Earth and other planets in orbit around the Sun, and it also keeps the Moon in orbit around the Earth.
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Tides: The tides observed on Earth are the result of Earth’s rotation as well as the gravitational influence of the Moon and the Sun.
Interesting Facts
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Weight Difference on Mars: Gravity on Mars is weaker than on Earth. A person who weighs 200 kg on Earth would weigh only about 76 kg on Mars.
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History of Science: It is believed that Isaac Newton was inspired to develop his theory of gravity by observing an apple fall from a tree.
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Einstein and Modern Physics: While Newton’s “law of universal gravitation” gives accurate results in most cases, modern physics explains gravity using Albert Einstein’s “general theory of relativity.”
Gravity on Earth
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Free-Fall Acceleration: On Earth, the acceleration caused by gravity is on average 9.8 m/s². If air resistance is ignored, the speed of a falling object increases by 9.8 meters every second.
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Gravity Beyond the Atmosphere: Just 100 km above the Earth’s surface, gravity is only about 3% weaker than at the surface.
Humans and Gravity
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The human body can withstand significant g-forces to a certain extent. This is seen in aviation maneuvers, space training, and sports.
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U.S. Air Force test subject John Stapp voluntarily endured an acceleration of 46.2 g — the highest ever recorded in humans.
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Formula 1 drivers experience about 5 g during heavy braking. In crashes, however, the forces can exceed 100 g.
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Some roller coasters in amusement parks produce forces between 4 and 6 g.
Applications of Gravity
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Potential Energy: The higher an object is positioned, the greater its gravitational potential energy.
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Trebuchets in the Middle Ages: Medieval siege weapons known as trebuchets used gravitational potential energy of heavy counterweights to hurl stones and projectiles over long distances.
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Modern Use: Today, gravitational energy is harnessed in hydroelectric power stations, where falling water converts its energy into electricity.