Nature of Forces
Main Ideas
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Force is necessary to stop or move an object.
Force leads to motion.
Force can act even at a distance.
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Objects tend to stay at rest.
Objects resist change.
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Force is a vector quantity with magnitude and direction.
SI Unit for force is Newton (N).
1 N of force gives a 1-kg mass an acceleration of 1 m/s².
1 N is equal to 1 kg m/s².
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Force can initiate movement from rest.
Force can stop a moving object.
Force can alter the direction of a moving object.
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Types of forces: Gravitational, Electromagnetic, Weak Nuclear, Strong Nuclear, Fundamental Forces.
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Contact and non-contact forces exist (e.g., gravity, tension, push, pull).
Non-Fundamental Forces are examples of non-contact forces.
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The aim is to unify 3 fundamental forces into one basic force.
Grand Unified Theory seeks to combine electromagnetic, weak nuclear, and strong nuclear forces.
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Theory of Everything aims to unify all fundamental forces.
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Electroweak Force was formed by combining EM force and weak nuclear force.
Sheldon Glashow, Abdus Salam, and Steven Weinberg won the 1979 Nobel Prize in Physics for this.
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Connection between individuals or objects is discussed.
The concept of being connected is explored.
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Contact Forces require physical contact between objects.
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Non-Contact Forces (action-at-a-distance or field forces) do not require physical contact to affect objects.
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Applied force is exerted on an object by another object or person.
The direction of applied force depends on how it is applied.
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Normal Force (N) is a pressing force directed towards an object perpendicularly.
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Frictional force results from intermolecular forces between surfaces.
It acts parallel to the surface.
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Frictional force is calculated as f = µN, where µ is the coefficient of friction and N is the normal force.
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Air Resistance Force is a type of frictional force.
It is negligible but noticeable in fast-moving or large objects.
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Tensional force is transmitted through strings, ropes, or wires.
It always acts away from the object.
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Spring force is exerted by a spring on an attached object to restore its position.
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Force of Gravity (Weight) is the attraction of a massive body towards an object.
Weight is calculated as W = mg.
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Weight is calculated as W = mg, where g = 9.8 m/s² and m is the object's mass in kg.
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Electrical force exists between charges.
Magnetic force exists in magnets.
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Balanced Forces are equal and opposite, resulting in zero net force.
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Unbalanced Forces have a nonzero net force, causing acceleration.
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Mass is the amount of matter in a body, while weight is the force due to gravity.
Mass is a scalar quantity, weight is a vector quantity.
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Weight is calculated as W = mg, where g = 9.8 m/s² on Earth.
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Sample Problem 1 involves calculating weight on the moon.
Lynne's weight on the moon is 163.0 N.
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Sample Problem 2 involves finding the acceleration of gravity on Mars.
The acceleration of gravity on Mars is 3.8 m/s².
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Practice Exercises involve calculating weight on the moon and comparing masses