The frequency and wavelength of a transverse wave on a string are 340 Hz and 0.70 m, respectively. The tension in the string is 390 N. What is the linear density of the string

Two objects of different mass start from rest, are pulled by the same magnitude net force, and are moved through the same distance. the work done on object 1 is 900 j. after the force has pulled each object, object 1 moves twice as fast as object 2. how much work is done on object 2?