Hi, I am working with the vibration motor in smartphone. I want to calculate to force comes from the vibration motor through time. In this case, I only measure the force in 3 direction, like x, y and z axes. I expect it has sinuous form but I dont know exactly the mathematics equation to represent it. Here is the description of the vibration motor (a patent) http://www.google.com/patents?hl=vi&lr=&vid=USPAT6323757&id=1RgIAAAAEBAJ&oi=fnd&dq=mobile+vibration+motor&printsec=abstract#v=onepage&q=mobile%20vibration%20motor&f=false Anyone know about mathematical model of inertial force of eccentric weight? Please help me. My major is Computer Science, so could you explain it simple also?