Okay, I have this problem that I've been having trouble with. It seems like a simple problem, but I keep getting the wrong answer and I don't know where I'm making the error. Maybe one of you can help me target the problem. =) The problem is as follows:

Well, firstly I converted the 50.0 hp into watts by multiplying it by 746 (because one hp equals 746 watts). I got 37300 watts. Then using the formula [tex]P=\frac{W}{\Delta t}}[/tex], I plug in 6.40 x 10^{5} J as P(ower) and 6.40 x 10^{5} as W(ork). When I calculated it, I get .058 seconds for t. However, the correct answer is 17.2 seconds. Can anybody tell me where I'm going wrong and waht I need to do?

Ohhh... haha. Whoops, I was just making a calculation error. Thanks! Okay I get it. I have another question though. In the following problem:

Okay, for this problem, I'm not quite sure how to approach it. Initally, I thought I had to simply use the formula [tex]P=\frac{Fd}{\Delta t}}[/tex] to solve it by pluggin in 4.0 x 10^{3} N as F and 3.00 m as d, and jsut put in one second for t. However, when I calculated it, it didn't come out to the correct solution so I'm assuming that this approach was not right. How then, would I solve this problem?