a boy weighs 80 lb and is hanging uniformly from a bar, how do you find the force in each of his arms at t=2s if the bar is moving upward with a.)constant velocity of 3ft/s, b.) a speed of (4t^2) ft/s?

Answer 1

a) In the first case, since he is not accelerating, the total force pulling his arms up equals his weight. It will probably be divided equally between the two arms.

b) In this case,
total force on both arms = M g + M a
= (W/g) * (32.2 + 4 ft/s^2)

W/g is the mass of the boy in units of "slugs" (2.48 slugs)