Mass of the object and collsions I'm using the game engine and I have a cylinder (rigid body) which has to crash with another objects. My problem is when I set the propertie "Radius" because at the end of the cylinder there is a sphere that represents that mass of the cylinder that can collide with other objects, so if I change the value of the propertie "Radius" the sphere turns bigger or smaller. I don't know how to do disappear that sphere because I need th cylinder can hit other objects with all its geometry, not only in the end. I try to use "Collision Bound" type "Cylinder" but the behaviour is very similar.

Look at the screenshots!

Here we can see the sphere at the end of the cylinder



The end of the cylinder that has the sphere hits the ball



But the other tip of the cylinder break through the ball



How could I fix this?
As your Cylinder should be presented as cylinder towards the physics too, you need to change the Properties/Physics/Collision Bounds/Bounds to Cylinder. You will see the dotted cage (representing the physics shape) will turn into a cylinder too. 

Hint: If the dotted mesh is not aligned correctly then turn the display mesh in edit mode that it fits.

Alternative: Bounds: Convex Hull or Triangle Mesh - be aware they are more expensive.

I hope it helps