Physics Help Forum Is there a difference between the coefficients of static friction/kinetic friction?

 Kinematics and Dynamics Kinematics and Dynamics Physics Help Forum

 Apr 25th 2009, 05:59 PM #1 Senior Member   Join Date: Mar 2009 Posts: 129 Is there a difference between the coefficients of static friction/kinetic friction? The following are questions from my physics book for a lab that our teacher is not going to do but he announced a test on the whole dynamics chapter and I get the rest but would like to know the answers to these unanswered questions in the book to increase my understanding of the subject. 1) Is there a difference between the coefficients of static friction and kinetic friction? 2) Is the coefficient of static friction or kinetic friction larger? 3) What kind of situation is required in order to feel the difference in the two types of friction? 4) What effect will a different surface material have on each of the coefficients? 5) What are situations in which friction is helpful? What are situations in which friction is undesirable? How is technology used in situations to either increase or reduce friction? Any help would be greatly appreciated! Thanks! Last edited by s3a; Apr 25th 2009 at 06:03 PM.
 Apr 25th 2009, 06:14 PM #2 Senior Member     Join Date: Apr 2008 Posts: 815 1)In general yes. 2)Static friction 3)Pushing a heavy object. You can push and it won't move, but once it moves he does it quite fast. 4)The more the surfaces are rough, the greater the coefficients of friction are. 5)It's helpful for life, for example. If there was no friction, it would be impossible to change your position. So you would stay where you are born all your life. Clearly life wouldn't have proliferated without friction. It's also helpful for a car to decelerate. It's helpful to create fire with 2 stones. It's undesirable for pendulums and also for planes. __________________ Isaac If the problem is too hard just let the Universe solve it.
Apr 26th 2009, 11:46 AM   #3
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Join Date: Nov 2008
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 Originally Posted by s3a How is technology used in situations to either increase or reduce friction? !
Decrease:Rolling friction is far less hence you can see circular Tyre not square ones.

Increase:I my Rubber Tyre and Pen-grip.

Another interesting question to you--*you must have seen this *---WHich one do you find easier to pull or push

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