Two friends, Joe and Sam, go to the gym together to strength train. They decide

Question

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 30.0 kg barbell. Joe is taller than Sam which means Joe's arms are 69.6 cm long while Sam's are 61.2 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.

Explanation / Answer

Amount of work = F x d .. for the same force, raising a greater distance means more work is being done on the lift. The question appears to ask for the work done on the lift part only .. then the work done by Joe is the greatest. If this answer is wrong .. then the question means the work done over a complete cycle .. including lowering then raising the weight.(and you can justifiably complain that the question doesn't make this clear). In this case the net work could be zero for both of them (as equal amounts of + and - work are done) .. and then .. WSam = WJoe = 0

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