Consider the following ConcepTest. A platelet is drifting with the blood flowing through a horizontal artery. As the platelet enters a constriction, does the blood pressure increase, decrease, or stay the same?

1.
E.
Mazur
,
Peer Instruction: A User's Manual
(
Prentice Hall
,
Upper Saddle River, NJ
,
1997
), pp.
173
174
.
2.
Many standard physiology textbooks incorrectly make the unqualified statement that blood flows from regions of higher to lower pressure in the body, in contrast to what happens as the blood leaves the constriction in Fig. 1. For example, see
G.J.
Tortora
and
S.R.
Grabowski
,
Introduction to the Human Body: The Essentials of Anatomy and Physiology
, 5th ed. (
Wiley
,
New York
,
2001
), p.
376
.
3.
Compare, for example, Checkpoint 4 in
J.
Walker
,
D.
Halliday
, and
R.
Resnick
,
Fundamentals of Physics
, 10th ed. (
Wiley
,
Hoboken, NJ
,
2014
), p.
403
.
4.
For a discussion of similar student difficulties with arithmetical reasoning
, see
A.B.
Arons
,
Teaching Introductory Physics
(
Wiley
,
Hoboken, NJ
,
1997
).
5.
C. E.
Mungan
, “
The Bernoulli equation in a moving reference frame
,”
Eur. J. Phys.
32
,
517
520
(
March
2011
) and references therein.
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