Question
explain
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 48.0 kg barbell. Joe is taller than Sam which means Joe's arms are 67.6 cm long while Sam's are 60.0 cm. Calculate the work done by Joe, W_Joe when he raises the barbell to finish one repetition. The acceleration Joe due to gravity is 9.81 m/s^2. W_Joe =
Explanation / Answer
We use formula,
Work = Force*distance
WJoe = Weightbarbell*height
WJoe = mbarbell*g*h
WJoe = 48.0*-9.81*0.676
WJoe = 318.0 J