Check out the book The gift of fear and in sheep ' s clothing . The first book will help you assess risk in this type of situation . The second will help you see manipulative behavior . Telling him no isn ' t working . Talking to him bluntly won ' t either . Cutting contact might work . Tell your friends and family what is going on . Tell them not to talk to him . He will probably up the ante if you ignore him . He ' ll find some way to get you to respond . He might call your place of work , call an elderly family member . But resuming contact will not help things , just keep him hoping . <| sep |> RPM times circumference gives speed . Friction is really only something you have to worry about if the wheel slips and loses traction .