function blowElement(element,x,y,z,speed)
local ex,ey,ez = getElementPosition(element)
x,y,z = x-ex,y-ey,z-ez
local dist = math.sqrt(x*x+y*y+z*z)
x = x*speed/dist
y = y*speed/dist
z = z*speed/dist
setElementVelocity(element,x,y,z)
end
Didn't test, but it should work.