I am looking for a way to calculate the stopping force for a pendulum but have two problems here. Number one is that I can not find any information on a (non-experimental) way of calculating the force a pendulum would have if you pulled against its direction of motion or put something in front of it. Second: I need to stop it after an initial impact and was wondering if anyone knows of a way to calculate the energy lost to a pendulum after impact. Thanks! Any and all help is appreciated!