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 37.5 kg barbell. Joe is taller than Sam which means Joe's arms are 69.2 cm long while Sam's are 59.0 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.

wjoe= J

Remember Sam also does the exercise. How does the amount of work Sam does, WSam, lifting the weight compare to Joe? Choose the correct operator from the list below.

WSam = WJoe
WSam > WJoe
WSam < WJoe

Explanation / Answer

Work done by joe = mgh

= 37.5*9.8*0.692

= 254.31J

by sam = mgh

= 37.5*9.8*0.59

216.83J

clearly work done by Joe is greater than sam by 37.49J

Wsam < Wjoe

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