Let us say we have a have mass concentrated at the end of a string(simple pendulum).Let us say the pendlum is set in motion and then eventually due to energy loss through air resistance, the amplitude of the oscillation will reduce and eventually the pendulum comes to rest. These damping forces are taken in problems as: Damping force=(Damping Coefficient) x velocity of vibration My questions are: 1. how is the damping force proportional to velocity of vibration??? 2. What is this damping coefficient?What does the damping coefficient physically denote??