# General jME Physic questions!

I played with the physic of jME, but my results weren't very realistic.

Therefore I have some questions, if nobody mind.

setMass(x)  Is x the SI unit kg ? (or something else?)

addForce(y)  What kind of SI is this? Joule? How much y need I to move y 1 meter?

addForce seems to be active for an enternity, but I want tog give my box only a push in the right direction.

More Mass should reduce the impact and long lasting power of the push.

How can I do this?

THX

Maybe the addForce( Vector3f force, Vector3f at ) method would help:

/**

* Add a force to be applied to this node at a given relative location. The force vector is given

* in world coordinate space. The force is applied in the next computation step and is cleared afterwards.

* Thus this method has to be called frequently (before each physics step) if a constant force should be applied.

*

* @param force force to be added (world coordinate space)

* @param at    position of the object where the force should be applied (relative to the center of mass)

* @see PhysicsUpdateCallback

*/

The units are whatever you want them to be. It will help you to read the documentation found at the ODE website, or read through some discussions over at the users group.

The reason an object, say a sphere, will roll forever is because of the lack of friction or the materials used. There are many ways to utilize the engine, and tailor the behaviors to what you would like to achieve. If you can’t dig up some info on what you would like to specifically do, or are not sure how to look for it then post back here. I’ll help you as much as I can. Going to Hawaii tonight though, so don’t expect to hear from me this weekend!

Going to Hawaii tonight though, so don't expect to hear from me this weekend!

I am jealous!  Have fun and catch a tan m8 :)!

```JavaDoc:     /**      * Add a force to be applied to this node at a given relative location. The force vector is given      * in world coordinate space. The force is applied in the next computation step and is cleared afterwards.      * Thus this method has to be called frequently (before each physics step) if a constant force should be applied.      *      * @param force force to be added (world coordinate space)      * @param at    position of the object where the force should be applied (relative to the center of mass)      * @see PhysicsUpdateCallback      */```

Thanks! Thats exactly what I was searching!

Have fun and don't let yourself get eaten by a shark^^