The A992 steel posts are “drilled” at constant angular speed into the soil using the rot...

The A992 steel posts are “drilled” at constant angular speed into the soil using the rotary installer. If the post has an inner diameter of 200 mm and an outer diameter of 225 mm, determine the relative angle of twist of end A of the post with respect to end B when the post reaches the depth indicated. Due to soil friction, assume the torque along the post varies linearly as shown, and a concentrated torque of 80 kN m acts at the bit.