# Problem: Biomedical measurements show that the arms and hands together typically make up 13.0 % of a persons mass, while the legs and feet together account for 37.0 % . For a rough (but reasonable) calculation, we can model the arms and legs as thin uniform bars pivoting about the shoulder and hip, respectively. Let us consider a 76.0 kg person having arms 68.0 cm long and legs 93.0 cm long. The person is running at 12.0 km/h , with his arms and legs each swinging through 30° in 1/2 slarge{frac{1}{2};{ m s}}. Assume that the arms and legs are kept straight.a) What is the average angular velocity of his arms and legs?b) Calculate the amount of rotational kinetic energy in this persons arms and legs as he walks.c) What is the total kinetic energy due to both his forward motion and his rotation?d) What percentage of his kinetic energy is due to the rotation of his legs and arms?

###### Problem Details

Biomedical measurements show that the arms and hands together typically make up 13.0 % of a persons mass, while the legs and feet together account for 37.0 % . For a rough (but reasonable) calculation, we can model the arms and legs as thin uniform bars pivoting about the shoulder and hip, respectively. Let us consider a 76.0 kg person having arms 68.0 cm long and legs 93.0 cm long. The person is running at 12.0 km/h , with his arms and legs each swinging through 30° in 1/2 s. Assume that the arms and legs are kept straight.
a) What is the average angular velocity of his arms and legs?
b) Calculate the amount of rotational kinetic energy in this persons arms and legs as he walks.
c) What is the total kinetic energy due to both his forward motion and his rotation?
d) What percentage of his kinetic energy is due to the rotation of his legs and arms?