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# Circular Motion and other Applications of Newton Law

الكلية كلية التربية للعلوم الصرفة     القسم قسم الفيزياء     المرحلة 1
أستاذ المادة فؤاد عطية مجيد       29/05/2018 09:15:14
Tension
When a cord (or cable, or other such object) is attached to a body and pull taut. The cord pulls on the body with force T ? directed away from the body and along the cord. The force is often called a tension force because the cord said to be under tension.
5.13 Frictional Force
Frictional forces play an important role in the motion of real objects. Surface in constant exert two forces on each other:
Normal; force ? to surface
Parallel ; friction, force of friction always opposes
relative motion or potential relative motion of the surface.
Arise from adhesion between atoms in the two surfaces.
Proportional to normal force between surfaces
Independent of area of constant
Independent of speed
Kinetic Friction (surface in relative motion)
f_k=?_k N
?_k coefficient of kinetic friction (0N contact (normal) force
Proportional to N
f_k parallel to the surface of contact .
Opposite to the direction of the motion
?_k depends on the nature of the materials, ?_k independent of v over wide range
Friction force on each interacting body is opposite in direction to the motion of that body relative to the other.
Static Friction
Frictional forces also acts between surfaces that at rest (no relative motion)
Object at the rest require a non-zero force to start them moving
f_s??_s N
?_s coefficient of static friction
Force of static friction can have any magnitude between zero (when there is no other force parallel to the surface) up to a maximum due to ?_s N. Equality sign holds when motion is about to start
Proportional to normal force
Independent of area
Opposite to the lateral push that tries to move the body
Usually ?_s>?_k, so that once block starts moving it will take less force to keep it from acceleration
?_s depends on nature and condition of surfaces

المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .