CH-6 Review

# CH-6 Review - CH-6 Review Further Apps. To Newton’s Laws...

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Unformatted text preview: CH-6 Review Further Apps. To Newton’s Laws Prepared By: Fady Morcos Friction • Friction Force arises from adhesion between two surfaces. – Atoms from the block form bonds with atoms from the table surface. – When the block slides, these bonds are continually ruptured and formed again. – You need a minimum force for the block to break those bonds and start moving. – Bond strength is a function of the materials under study (block & table) and the weight of the sliding object. Static Friction • Static Friction – Object initially at rest. – Friction force act to prevent object from moving. – Force has to be sufficiently large to overcome friction. – F > fs to start motion. – fs increases as F increases. – The max magnitude of fs is given by fs,max = µsN Where µs is called the coefficient of static friction. – If F > f , the block will start moving. Kinetic Friction • Kinetic Friction – Object Already in motion. – Friction force act to decelerate the object. – The magnitude of fk is given by fk = µkN Where µk is called the coefficient of kinetic friction. – Note: friction force is proportional to the magnitude N, but points opposite to the direction of motion. – Which orientation experiences more friction? Spring Force; Hooke’s Law • Restoring Force: The force by which a body resist deformation. • Hooke’s Law: – The magnitude of the restoring force is directly proportional to the deformation. • Spring Force – Fs = -kx Where k is the spring constant. What are the units of k? Courtesy of: http://phy-61062.blogspot.com Uniform Circular Motion • Recall centripetal acceleration: v2 a= r • According to Newton’s 2nd Law [ F = ma] – This acceleration must be caused by a net force having the same direction as that of a. mv 2 F = ma = r – Force is dubbed Centripetal Force • However, it is not an actual force, it is a resultant force from tension, gravity, normal force…etc. • Doesn’t appear on FBD. ...
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## CH-6 Review - CH-6 Review Further Apps. To Newton’s Laws...

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