Chapter 1, Problem 78RE

Fencing a Garden A determined gardener has 120 ft of deer resistant fence. She wants to enclose a rectangular vegetable garden in her backyard, and she wants the area that is enclosed to be at least 800 ft2 . What range of values is possible for the length of her garden?

Blood Flow As blood moves through a vein or an artery, its velocity v is greatest along the central axis and decreases as the distance r from the central axis increases see the figure. The formula that gives v as the function of r is called the law of laminar flow. For an artery with radius 0.5 cm, the relationship between v in cm/s and r in cm is given by the function v(r)=18,500(0.25r2)0r0.5 a Find v(0.1)andv(0.4). b What do your answers to part a tell you about the flow of blood in this artery? c Make a table of values of v(r)forr=0,0.1,0.2,0.3,0.4,0.5. d Find the net change in the velocity v as r changes from 0.1 cm to 0.5 cm.