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Diagram of centripetal force on a roller coaster
What makes planetary bodies like the Moon or Earth stay in orbit. What makes it possible for an object to stay in a circular path even when our understanding of the forces affecting it would lead us on first thought to assume otherwise? The reason behind this is centripetal force. Centripetal force is the exertion of force that keeps an object in a curved path when in movement. It is often confused for centrifugal force. So how does it work? The answer is actually a simple case of a blending of opposing forces.
Any object in the universe is under the influence of more than one exerted force at any given time. For example a person standing is experiencing the force of gravity, the force exerted by the air around and the resisting force of the ground beneath their feet. However there is a key difference between an object at rest and one moving. That difference is that the resting object has its system of forces perfectly balanced. The moving object does not.
In the case of a moving object two forces unbalanced just right can create an interesting movement. In the case of centripetal force you have an object that is moving in a straight line normally that also experiences a force pulling it inward towards a focal point. Take the example of a ball on a string. The ball is naturally inclined to go straight but the pull of the string as you swing the ball around keeps it in its circular path. The inward force is not strong enough to overcome the force of the ball in motion.
The centripetal force effect is seen in nature when we see the gravity of a planet exerted on its satellites. The satellites are moving at too high a velocity to fall towards the planet’s center of gravity. However the pull of gravity is strong enough to still bend their path into an orbit.
Centripetal force can then be seen to be one of the fundamental forces needed to understand the movement of celestial bodies. It is also important for spaceflight as it has been used to help launch artificial satellites and help send deep space probes to distant planets. It is also being looked into as a possible source of artificial gravity for future manned space missions. This just shows you some of the many ways the principle can be adapted.
If you enjoyed this article there are several others on Universe Today that you will enjoy. There is a great article about the gravity of the Earth. There is also an interesting article about Freefall.
There are also some great resources online. The Georgia State University website has some great information on centripetal force. There is also a great article on the Howstuffworks.com.
You can also check out astronomy cast. Episode 145 Interstellar travel is an interesting show.
Sources:
Wikipedia
GSU Hyperphysics
The Physics Classroom
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