A standard man does reverse curls in a gym. He holds his arms straight, using an overhand grip to hold the bar. If the mass of the bar is given as 127 kg, what is the tension in each of his shoulders? Consider the weight of the arm and the weight of the bar. Note: Use 4.9kg as the mass of the arm of the standard man.
Take a look at this video and see what you think.
http://www.exrx.net/WeightExercises/Brachioradialis/BBReverseCurl.html
Stresses will be higher when the bar is decelerating, but they probably want you to ignore that.
Assume each shoulder supports half the weight of the barbell, plus the arm's own weight.
To find the tension in each of the man's shoulders while performing reverse curls, we need to consider the weights of both the bar and the arm.
First, let's calculate the gravitational force acting on the bar. The weight (force due to gravity) can be found using the equation:
Weight = mass x gravitational acceleration
Given that the mass of the bar is 127 kg and the gravitational acceleration is approximately 9.8 m/s^2, the weight of the bar is:
Weight of the bar = 127 kg x 9.8 m/s^2 = 1246.6 N (approximately)
Next, let's calculate the gravitational force acting on the arm. The mass of the arm is given as 4.9 kg, so the weight of the arm is:
Weight of the arm = 4.9 kg x 9.8 m/s^2 = 48.02 N (approximately)
Now, let's consider the forces acting on the man's shoulders. When performing reverse curls, the tension in each shoulder needs to counterbalance the combined weight of the bar and the arm.
So, the tension in each shoulder can be calculated as the sum of the weights of the bar and the arm:
Tension in each shoulder = Weight of the bar + Weight of the arm
Tension in each shoulder = 1246.6 N + 48.02 N = 1294.62 N (approximately)
Therefore, the tension in each of the man's shoulders while performing reverse curls is approximately 1294.62 N.