Originally Posted by

**dejawolf**
that doesn't really answer my question.

but then again maybe my question was too complex. i'm trying to get the basics down, and you throw all sorts of advanced stuff on my lap.

ok, here's a simpler question:

i believe an object traveling in a circular motion at 40kph has the same kinetic energy as an object traveling 40kph in a straight line.

is this true or false?

i also believe that applying a force of 190 newtons as torque is different to applying it in a linear motion. is this true or false?

and please, give me an answer, instead of telling me "its not that easy", then going on a tirade about how difficult it is, before in the end never giving me an answer in the first place. otherwise you just sweep whatever fundament i've been trying to build away from under my feet, and leave me to build on bare ground again.

Kinetic energy is dependent on the scalar speed rather than on the vector velocity. So an object traveling at 40 kph has the same kinetic energy whether it is traveling along a line, around a circle, in a corkscrew pattern or any kinematic description.

Force and torque are different things. Force is a vector quantity that is independent of the point of application. F=ma works no matter where the force is applied.

Torque is a bit different. Torque alone makes no sense. To define torque you not only have to define the vector, but also a point about which the torque is to be taken, or equivalently if it is generated by a force the vector from the point at which you want torque to the point of application of the force (think lever arm). More precisely if you have a point P, a vector R and a force F applied at the point represented by a displacemenet from P by R then the torque T at P is given by T= R X F, where X is the vector cross product.

You can't apply a force of 190 Newtons as torque. The units of torque are Newton-meters, which is the same units that describe energy, but torque is NOT energy. Torque is a vector quantity, while energy is a scalar quantity. Torque is the cross product of force and distance while energy is the scalar (dot) product of force and energy.

While you can derive the equations for angular motion and conservation of angular momentum from the linear equations for a system of particles (it is pretty easy and is one of the first things you would see done in a book on classical mechanics, such as the text by Goldstein), I don't think you can reverse the process.

Here is a Wiki article on torque.

http://en.wikipedia.org/wiki/Torque