A 40.0 kg child sits on a swing with two vertical ropes that are each initially 4.18 m long. Each rope increases in length by 2.0 cm. (a) Determine the strain on each rope in both decimal and percentage notation. (two significant digits) %. b) If the cross-sectional area of each rope is 4.5 x 10^{-4} m^{2} , what is the stress on each rope? (two significant digits)