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Five objects of equal mass are shown below together with the axis about which th

ID: 1893879 • Letter: F

Question

Five objects of equal mass are shown below together with the axis about which they are rotating. Select from the pull-down menus the objects in order of increasing rotational energy, with 1 having the smallest rotational energy and 5 having the highest rotational energy.

a) Solid Cylinder, about cylinder axis with R = 3 m and gw = 4 rad/s

b) Thin Spherical shell, about any diameter, with R = 3 m and gw = 4 rad/s

c) Thin rod, about axis through center, perpendicular to the length with l = 9 m and gw = 4 rad/s

d) Thin cylindrical shell, about cylinder axis with R = 2 m and gw = 5 rad/s

e) Solid Sphere, about any diameter, with R = 4 m and gw = 4 rad/s

Explanation / Answer

rotational energy = 1/2 I2

for a) rotational energy = 1/2 x (1/2 x m x 9 ) x 16 = 36m

b) rotational energy = 1/2 x (2/3 x m x 9 ) x 16 = 48m

c)  rotational energy = 1/2 x (1/12 x m x 81 ) x 16 = 54m

d)  rotational energy = 1/2 x ( m x 4) x 25 = 50m

e)  rotational energy = 1/2 x (2/5 x m x 16 ) x 16 = 51.2m

order is a) < b) < d) < e) < c)