Question

After a busy grocery shopping trip, you are carrying multiple bags on your arm to get every-

thing into the house quickly. You have one bag containing 15 kg of groceries in your hand and another10kgbag8cmupyourarm. Yourlowerarmis28cmlongandhasamassof3kg. Your your bicep is connected to your lower arm 3 cm towards your hand from your elbow. The elbow is the hinge between your lower arm and the humerus bone of the upper arm. The humerus is 24 cm long and has a diameter of 2 cm.

(a) If your arm is at an angle of 10◦ below the horizontal, what is tension in your bicep? You can assume the tension from the bicep is perpendicular to the lower arm.

(b) If the Young’s modulus of the humerus is 15×109 N/m2, how much is the bone compressed in this situation? You can assume the humerus is vertical and that only the vertical force contributes to the compression.

Answer 1