1550078481-Ordinary_Differential_Equations__Roberts_

(jair2018) #1
Applications of the Initial Value Problem y' = f(:r, y); y(c) = d 145

140

120

100

80
y(x)
60

40

20

0

(^0 2 4) x 6 8
Figure 3.13 Numerical Approximation to the IVP:
y' = 32 - .25y; y(O) = 20
EXERCISES 3 .5
10
l. Write the equation for the velocity of a falling body, if the air resist-
ance is proportional to the squ are of the velocity. Numerically compute


and graph the velocity on the interval [O, 10], if g = 32 ft/sec^2 , if the

constant of proportionality is c = .25, and if the initial velocity is v(O) =

20 ft/sec. Estimate the terminal velocity in this case.


  1. Write the differential equation for the velocity of a falling body, if t he
    air resistance is proportional to vl.^6. Numerically compute and graph


the velo city on the interval [O, 10], if g = 32 ft/sec^2 , if the constant of

proportionality is c = .25, and if the initial velocity is v(O) = 20 ft/sec.
Estimate the terminal velocity.


  1. Write the differential equation for the velocity of a falling body, if the
    air resistance is proportional to -JV. Compute and graph the velocity on
    the interval [O, 10], if g = 32 ft/sec^2 , if the constant of proportionality is
    c = .25, and if the initial velocity is v(O) = 20 ft/sec. Is there a terminal
    velocity? If so, estimate its value.

  2. A parachutist jumps from a n airplane, falls fr eely for 10 seconds and
    then opens his parachute. Assume the parachutist's initial downward


velocity was v(O) = 0 ft/sec, assume the air resistance is proportional to

vl.^8 , and assume the constant of proportionality without the parachute
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