Al. The centroid, or centre of mass, Cm = (x; y; z) as defined in Section 15.6 can be used to determine if a 3D solid will stand up or fall over (under gravity). The key calculation involves showing that the location of the point Cm is vertically over the base of the object - if so, it will stand up. Your goal here is to figure out the range of heights H so that the portion of the cone x2 +y? = (z + 1)2 for 0