1. The problem statement, all variables and given/known data (I've summarized) A man applies to a sled 1000N parallel to the ground and pushes the sled a total displacement of 30m. The mass of the sled is 250N and [itex]\mu[/itex]k = 0.55, how much work does the man perform? If done over 12.8s, how much power does he exhibit? 2. Relevant equations W=Fdcos[itex]\theta[/itex] and P=W/t 3. The attempt at a solution I calculated the work that the man did and only the man and got: W=1,000N(30m) = 30,000J Thus, P=30,000/12.8s = 2,343.75J/s If net work was asked, I realize that you would add the work done by the man and the work done by friction to arrive at lower values, i.e., W=25,375J and J=2,021.48J/s. However, my question to you all regards semantics. The instructor marked my question wrong whereas I believe it to be correct because she did not ask for net/total work done on the sled/in the system, thus man+friction, only "how much work does the [man] perform?" The only answer she accepted was the net work and I want to know if I have a legitimate reason to get credit back based on what was asked in the given statement.