- #1
xeguy
- 38
- 0
There's a disagreement going on in my department regarding whether the static frictional force does any work. My argument rests on the fact that static friction has zero displacement, hence zero work.
The other side gives the example of a system consisting of a block on a piece of paper, both sliding along due to the presence of an external force pulling the paper. The net force on the block is due to the frictional force between the block and paper. Their claim is that this net frictional force is caused by static friction, and since the paper is displaced with respect to the table the block-paper system is on, the static frictional force does work on the block.
I tried countering with the fact that the static frictional force is internal to the system, but they're hung up on the block moving wrt the table. Also, I tried to consider that this frictional force was not correlated with any reference frame that it was not in contact with, ie; block and paper can have similar frames, as well as table- paper, and system-table. No luck there. I know I'm not crazy, but maybe someone else has a better example to show that static friction cannot do work!
The other side gives the example of a system consisting of a block on a piece of paper, both sliding along due to the presence of an external force pulling the paper. The net force on the block is due to the frictional force between the block and paper. Their claim is that this net frictional force is caused by static friction, and since the paper is displaced with respect to the table the block-paper system is on, the static frictional force does work on the block.
I tried countering with the fact that the static frictional force is internal to the system, but they're hung up on the block moving wrt the table. Also, I tried to consider that this frictional force was not correlated with any reference frame that it was not in contact with, ie; block and paper can have similar frames, as well as table- paper, and system-table. No luck there. I know I'm not crazy, but maybe someone else has a better example to show that static friction cannot do work!