Models however, also have limitations. The model used for electric circuits by scientists today makes use of the idea that all substances contain electrically charged particles (see the focus idea Macroscopic versus microscopic properties).
Depending on the materials used, a driveway can be utilitarian, like gravel, asphalt, or concrete, or decorative, like stamped asphalt, stamped concrete, or cobblestone. Typical costs: A gravel driveway starts at roughly $0.75-$3 or more a square foot, or $300-$1,000 for a 12'x25' single-car driveway. Costs can double for a roadway-quality driveway. Loose gravel will need replenishing periodically, but a correctly designed, installed and maintained gravel driveway can last 50-100 years or more.
The cost of gravel is generally $0.79 per square foot. Calculate the amount of gravel that will be needed and then contact local quarries for pricing. Remember to add in the delivery fees for the gravel. The cost of a concrete slab will vary depending upon the size of the slab as well as the thickness.he cost of gravel is generally $0.79 per square foot. Calculate the amount of gravel that will be needed and then contact local quarries for pricing. Remember to add in the delivery fees for the gravel. The cost of a concrete slab will vary depending upon the size of the slab as well as the thickness.