ray decides to paint the outside of his uncle's house. he uses a 4.0-m -long board supported by vertical cables at each end to paint the second floor. the board has a mass of 21 kg . ray (70 kg ) stands 1.0 m from the left cable. part a determine the magnitude of the force that the right cable exerts on the board. express your answer with the appropriate units. activate to select the appropriates template from the following choices. operate up and down arrow for selection and press enter to choose the input value typeactivate to select the appropriates symbol from the following choices. operate up and down arrow for selection and press enter to choose the input value type fr