Political boundaries are often formed by physical boundaries. An example of this is the Rio Grande River that separates the US from Mexico. An ethnographic boundary or a cultural boundary is a boundary line that runs along differences in ethnicity.
Steel has a density of about 490 pounds per cubic foot, which is more than three times the density of concrete, so the generally accepted density of normally reinforced concrete is 150 pounds per cubic foot which results in a cubic yard weighing 4050 pounds, but this depends on the quantity and grade of the rebar used.
If a truck is carrying 10 cubic yards, then the weight â¦ of the concrete is approximately 40,000 lb. The truck will weigh approximately 26,000 lb. for a total of 66,000 lb.