Attractive Forces

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m₁,m₂: mass of two objects; r: distance between two objects; G: gravitational constant

Gravitational Force

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M: Earth mass, m: mass of object, R: Earth radius, h: object’s height

Gravitational Acceleration

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At a height h above the normal surface of the earth

Near the sea level

Force Of Gravity

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Force of gravity on earth, a special case of Gravitational force

Newton's First Law

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F: forces acting on the object , v: velocity of the object, a: acceleration of the object

Newton's Second Law

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m: object’s mass(kg)

Newton's Third Law

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Linear Elasticity-Hooke's Law

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K: spring constant (n/m), x: displacement(m)

A Mass suspended by a spring

Force Of friction

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µ: coefficient of friction, N: normal force

            Fms = µN
                = µPcosα
                = µmgcosα