Imagine That a New Monorail System Is Being Planned for Sydney

Multiple Choice

Imagine that a new monorail system is being planned for Sydney. The trains will run on elevated tracks, 15 m high. A single square concrete post, 5 cm on a side, supports each segment of the track. How much of a sideways force can the track segments withstand without moving sideways by more than 1 mm? You may assume that the force shears the concrete support posts. The shear modulus of concrete is 2.2x109 N m-2.

A) 14 700 000 N.
B) 1 470 000 N.
C) 147 000 N.
D) 14 700 N.
E) 1470 N.