Its the product of torque and rpm that produce hp.
^^^ These are your words.... (making my point)
What I am (and have been saying) is HP is a measure of work. Work can't get done without force. That force in this case is torque. It is first the torque that overcomes the frictions and inertia to begin movement where work (HP) can be measured.
The ratio of available torque to the acting mass (minus friction) directly relates to acceleration. HP is not part of this equation. However, To keep an object moving work must be done.
Luckily, most engines that produce more HP also produce more torque, but there are engines where this isn't the case. A diesel for example, often makes much more torque than HP. This is why a large truck can accelerate a massive load easily but not be able to keep it moving on small grades.
Let's leave the units out of this for a moment... F=ma (Force=mass*acceleration) Since we want to solve for acceleration, a=F/m Notice: work isn't part of this equation.
I have a pretty solid understanding of the physics. In fact, I make my living bailing other engineers out of improperly sized motors... I'm not upset, but I am metaphorically dropping the mic. I'm out...