"A fire truck carrying a load of fire fighters and a large tank of water is about to cross a bridge that may not support the load. The chief suggests that some of the fire fighters get into the tank so the load will be less. Is this a good idea? Explain." I have no idea where to begin. I know that the fire fighters will displace a volume of water equal to their own, but I don't know if that would change the weight of the whole system. Any help or leads would be appreciated.