The objective of this paper is to bring out the responsiveness of the capacitive accelerometer with changes in the input acceleration. The performance analysis of the device is done using COMSOL MULTIPHYSICS .It is analysed that when the capacitance reaches a threshold value, amplifying the electric signal the air bag could be initiated.3D capacitive accelerometers which are less prone to noise and temperature variations. They reduce the severity of the accident by sensing the sudden increase in negative acceleration and deployment of the airbags. The dependency between the acceleration and the capacitance has been analysed. The sensitivity of the device with respect to forces in real time accident conditions is observed.