Rahul,
Sliding friction is independant of the area of contact. It only depends on the friction factor and the normal reaction perpendicular to the direction of the slide.
Sajit
-----Original Message-----
From: Rahul Kulkarni [mailto:rdk77@yahoo.com]
Sent: Thursday, July 01, 2004 2:18 PM
To: PipingDesign@yahoogroups.com
Subject: RE: [PipingDesign] Moment calculation
Hi Ganga ,
Friction is of diffent types.
Friction is a force. The force is equal to load acting on the plane because of the body * some factor for unit area. Coef. Of Friction. Friction acts when body tends to move. That means the till force which is trying to move the body is there the friction will oppose the movement of the body. That means a pipe just kept on the surface with no force acting on it will not experience any friction. When a staight pipe fixed at two ends and is resting on the surface is heated it will push the ends with some force. (depends on area of cross section , modulous of Elasticity and Change in length would have occured if the pipe is free to grow.).
Consider a straight pipe fixed at one end the other end is rididly connected to a heavy block which is resting on the surface. Because of the friction and Inertia of the block the block will show resistance to move when the pipe is heated. If the force generated by heating the pipe overcomes this force. The block will start moving. That means as soon as the force goes bellow this force of friction block will start moving. If you heat the pipe by an ammount which is not suuficient to move the block, The pipe will get stressed. As the force is acting on the block from one side and block is not moving means there is some force which is acting on the block. Which is of friction. So the force of friction will not vanish. All this is considering the force of friction remains constant with is not true once the body starts moving it decreases. It is called dynamic effect.
Rahul
RAHUL DEEPAK KULKARNI
GHARKUL 36 MANISHANAGAR
PANDHARPUR
PIN 413304
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[Non-text portions of this message have been removed] Received on Thu Jul 01 06:54:00 2004
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