I seem to be having a real difficult time doing a conversion that I confess I do not understand very well. What I am trying to do is convert x watts or x joules into dollars per year using a conversion factor of 3.9 cents per kW*h.

I know I am surely wrong, but I feel like I am trying to convert two dimensions into three so I kind of feel a little frustrated. I'll start from the beginning of my thinking process.

Lets start with Force. Force is mass multiplied by acceleration, or:

The units for this are:

or 1 newton, N

Next, lets measure force over a distance of a meter and call this Work. The units for work are:

or 1 joule, J

Next lets measure the amount of work we can do within the time interval of a second and call this Power. The units for power are:

or 1 watt, W

I feel I completely understand this so far, but after this I get lost. Aparently the next unit, the one that shows up on the utility bill is kW*h. What is this? This doesn't make sense to me. I could understand kJ*h as in an alternative for W, but not kW*h.