Friction

Friction

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Downloads: 0 - 10 Wednesday 15th March 2017 Report

Friction - Overview

------------ PAGE 1 ------------ Name Enrollment No:- Patel Avi H. 14100106048 Kotila Jayveer V. 15DTOD007 Mistry Aditya P. 15DTOD008 Pandya Dhrumil D. 15DTOD009 Guided By:- Prof. Mihir Naik -: Topic:- Friction ------------ PAGE 2 ------------ Content „H What is Friction? „H Limiting Friction „H Type of Friction „H Angle of Friction „H Co- efficient of Friction „H Angle of Repose „H Laws Of Friction ------------ PAGE 3 ------------ What Is Friction? „H When a body slide or tends to slide on a surface on which it is resting, a resisting force opposing the motion is produced at the contact surface. This resisting force is called friction or friction force. ------------ PAGE 4 ------------ Limiting Friction „H The maximum friction force that can be developed at the contact surface, when body is just on the point of moving Is called limiting force of friction . ------------ PAGE 5 ------------ Types Of Friction „H Static Friction:- „H Friction experienced by a body when it is at rest is called static friction. „H Dynamic Friction:- „H Friction experienced by a body when it is motion is called dynamic friction. „H Sliding Friction:- „H Friction experienced by a body when it slides over another body, is called sliding friction. „H Rolling Friction:- „H Friction experienced by a body when it rolls over another body is called rolling friction. ------------ PAGE 6 ------------ friction. ------------ PAGE 7 ------------ Angle of Friction „H The angle between normal reaction ( A) and resultant force ( R) is called angle of friction. „H It is also called limiting angle of friction. ------------ PAGE 8 ------------ Coefficient of friction „H The ratio of limiting friction ( F) and normal reaction ( N) is called coefficient of friction. „H ì= F/ N „H F = Friction Force „H N= Normal Reaction ------------ PAGE 9 ------------ Angle Of Repose „H With increase in angle of the inclined surface, the maximum angle at which body starts sliding down is called angle of friction. ------------ PAGE 10 ------------ Laws Of friction „H Laws of static friction „H The friction force always acts in a direction, opposite to t hat in which the body tends to move. „H The magnitude of friction force is equal to the external force. F= P „H The ratio of limiting friction ( F) and normal reaction ( N) is constant. F/ N= ì „H The friction force does not depends upon the area of con tact between the two surfaces. „H The friction force depends upon the roughness of the surfaces. ------------ PAGE 11 ------------ „H Laws of dynamic friction „H The friction force always acts in a direction, opposite that in which the body is moving. „H The ratio of limiting friction ( F) and normal reaction ( N) is constant and it is known as coefficient of friction ( ì). „H For moderate speeds, the friction force remains constant. But it decreases slightly with the increase of speed. ------------ PAGE 12 ------------ -: EXAMPLE:- „H A Pull of 50 N inclined at 30° to the horizontal is necessary to move a wooden block on horizontal table. If coefficient of friction is 0.20, find the weight of wooden block. Solution : P = 50 N ì = 0.20 ------------ PAGE 13 ------------ Resolve || to plane : F = 50 cos 30 º ì = F/ N F = 43.30 N 0.20 = 43.30/ N N = 216.5 Resolve ( perpendicular) to plane N 50 sin 30 º = W 216.5 25 = W W = 241.5 N ------------ PAGE 14 ------------ N
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