（a）Worm having one continuous tooth. （b）Worm gears.（c）Worm gearset. Reprinted with permission by Boston Gear Company.
After completer chapitre 3, you try to solve these problems:
Given numerical values for order-of-magnitude estimates for the follwing quantities. Explain and justify the reasonableness of the assumptions and approximations that you need to make.
● The number of cars that pass througn an intersection of two busy streets during the evening commute on a typical workday.
● The number of bricks that form the exterior of a large building on a university campus.
● The volume of concrete in the sidewalks on a university campus.
Repeat the exercise of Problem 1 for the following systems:
● The number of leaves on a mature maple or oak tree.
● The number of gallons of water in an Olympic-sized swimming pool.
● The number of blades of grass on a natural-turf football field.
The Space Shuttle orbiter takes about 90 minuites to comleter one trip around the Earth. Estimate the spacecraft's orbital velocity, in the units of mph. Make the approximation that the altitude of the spacecraft （approximately 125 miles）is small when compared to the radius of the Earth （approximately 3950 miles）.
An automobile assembly plant produces 400 vehicles per day. Make an order-of -magnitude estimate for the weight of the steel needed to make those vehicles. Explain and justify the reasonableness of the assumptions that you make.
