# Work done during sandpaper application on horizontal surface

1. Jan 22, 2008

### Jbum

1. a table is being sanded. in the process, the sandpaper is rubbed back and forth 30 times over a distance of 0.6m. it is pressed against the table with a normal force of 1.5N, and the coefficient of kinetic friction is 0.85. how much work is being done by the kinetic frictional force during this process?

2. W = Fd and f = N(uk)

3. force of friction = 1.5N (0.85) = 1.275N

therefore, work = 1.275N (0.6m) = 0.765J

is this correctly done??

and one more additional question as a side note: is it correct to say that no work is dont if the displacement from the original position is zero??

thanks for the help.

Last edited: Jan 22, 2008
2. Jan 22, 2008

### stewartcs

Don't forget about the 30 times for the first part of the question.

For the second question (side note), no that is not correct. Don't confuse the term displacement with distance. They have two different meanings. You can have a zero displacement even though you traveled some distance. For example, walk around in a big circle until you reach your starting point. Your displacement is zero, but your distance is non-zero, hence your work would be non-zero.

CS