Question

Jane sat in a chair and exercised a knee extension. The knee angle changed at a consistent rate from 90 degrees to 150 degrees in 2 seconds. Shank length was 0.4 m. Calculate (a) angular displacement of the knee, (b) angular velocity of the knee, (c) angular acceleration of the knee, (d) angular distance of the foot, (e) linear velocity of the foot, and (f) tangential lineal acceleration of the foot.

Answer 1

a)

= angular displacement = _f - _i = 150 - 90 = 60 deg = pi/3 = 1.05 rad

b)

t = time = 2 sec

angular velocity is given as

w = /t = 1.05/2 = 0.525 rad/s

c)

angular acceleration = = 0 rad/s²

since angular velocity is constant

d)

D = L = (0.4) (1.05) = 0.42 m

e)

v = L w = (0.4) (0.525) = 0.21 m/s