Two friends, joe and sam, go to the gym together to strength train. they decide to start off with an exercise called flat bench press. lying flat on a bench with their arms in an extended position, they slowly lower (to their chest) and then raise a barbell back to the starting position. they start off by using a 39.0 kg barbell. joe is taller than sam which means joe\'s arms are 67.8 cm long while sam\'s are 59.8 cm. calculate the work done by joe, wjoe, when he raises the barbell to finish one repetition. the acceleration due to gravity is 9.81 m/s2.