SUPPLEMENTARY MATERIAL: Sample Pre-Reading Assignments
https://docs.google.com/file/d/0B_hC3GvfyGPcbnZWSUo5XzFCQms/edit
PHYS 101
TARGETED READING___________________________________________________
15.1 Fluids. Contains the basic definition of fluids and mass density that we discussed
about this week in class.
15.2 Pressure. This is quite lengthy. You could start with the examples and read the
section as needed. Make sure you know how to calculate the pressure in a liquid at depth
d (equation 15.6). Example 15.2 illustrates an important concept.
SKIP SECTION 15.3 (we will come back to it later)
15.4 Buoyancy. You will look at buoyancy for the labs & tutorials (and we have begun
discussing it in class). Focus on Archimedes' principle and the examples. Think about
what it means for an object to float or sink, and what the volume of the displaced fluid is
in different situations.
ONLINE QUIZ QUESTIONS _______________________________________________
1. Looking at Figure 15.3, rank the forces on the water at the location of each hole (with
hole 1 being on top and hole 3 being on the bottom).
a. F1 = F2 = F3
b. F3 > F2 > F1
c. F1 > F2 > F3
d. F2 > F1 = F3
Feedback: Review pages 445-450. In a gas, the pressure is nearly the same at all
points; however, in a liquid the pressure increases with depth below the surface.
Since F = pA, the force will also increase with depth.
2. Look at the two containers in Figure 15.13. How would you best describe the pressure
at point p1 and p2?
a. p1 > p2
b. pi = p2
c. p1 < p2
Feedback: Review pages 448 - 450. It is important to look at the weight of the
water column above a point. Just because the cone holds more water does NOT
mean that the water pressure along the horizontal line changes (as long as the
liquid is connected, as is the case here). Also look at Figure 15.14.
3. The buoyant force on an object fully submerged in a liquid depends on (select all that
apply)
a. the object’s mass.
b. the density of the liquid.
c. the object’s volume.
d. the mass of the liquid
Feedback: Review pages 456 - 459. Think about why the density of the liquid is
more important than the mass of the liquid. Also look at equation 15.14.
4. Chose the statement below that is FALSE about buoyancy:
a. An object on a scale immersed in a fluid has a different apparent weight than it
does on a scale in air.
b. An object immersed in a fluid experiences an 'extra' force that makes it appear
lighter.
c. The mass of an object decreases when it is immersed in a fluid.
d. The relative density of the fluid as compared to an object will determine if it
floats.
Feedback: As we discussed in class, the MASS of an object stays CONSTANT. The
mass does not change (and gravity does not change). However one often thinks of
the 'effective weight' of an object in water as 'feeling lighter'. This is because there
is an EXTRA force: the buoyant force. It might be easier to refer to the 'net force'
on an object to avoid confusion.
5. Looking at figure 15.24 (located in the Example 15.9 Box), what can you say about
the relative densities of the unknown liquid (ρ_unkn), water (ρ_water), and the block
(ρ_block)?
a. ρ_water > ρ_unkn > ρ_block
b. ρ_block > ρ_water = ρ_unkn
c. ρ_block > ρ_unkn > ρ_water
d. ρ_block > ρ_water > ρ_unkn
e. ρ_unkn = ρ_water > ρ_block
f. ρ_unkn > ρ_water > ρ_block
Feedback: Review the Tactics Box on page 457. Comparing the average density
of an object, in this case a block, with the fluid density can tell you if the object
will float, sink, or be neutral. The block floats in BOTH the water and the
unknown liquid, but the block sits HIGHER in the unknown liquid, so the
unknown liquid must have a higher density than water.
BIOL 260
TARGETED READING___________________________________________________
Read section 46.5 (Movement) of Chapter 46: Animal sensory systems and movement
from your text book (p. 1095-1100) and take the corresponding pre-reading quiz online.
Skim the introductory paragraph of the "movement" section, and the section on
"Skeletons" p. 1095-1096
We will not be covering this material in any depth, so just focus on being able to answer
the following questions:
 Why are muscles organized into antagonistic muscle groups?
 How does this facilitate locomotion?
 You don't need to understand how the muscles in animals with hydrostatic
skeletons work together to allow locomotion. Just get a feel for how the system
works in animals with an endoskeleton
Read section the next section ("How do muscles contract") p. 1097-1100 carefully.
This is the most important part of the chapter, and will be the main subject of the
lecture
In the section "The sliding filament model" make sure you understand:
 The relationship between muscle tissue, muscle fibers, myofibrils and sarcomeres
(Figure 46.19)
 Why striated muscle has bands (striations) (compare Figure 46.19 to 46.20)
 What happens to the size of the bands during contraction
In the section "How do actin and myosin interact?" focus on:
 The steps shown in Figure 46.22
 Making sure you understand the role of ATP in the process
 You can skip Figure 46.21
In the section "How does relaxation occur", focus on:
 The role of troponin, tropomyosin, and calcium (Figure 46.23)
In the section "An overview of events at the neuromuscular junction?" focus on:
 Understanding the role of the T-tubule system
 How this controls Calcium release
You can skip the section "Muscle Types" (p. 1101)
ONLINE QUIZ QUESTIONS _______________________________________________
1. Look at figure 46.20. When a muscle fiber shortens (contracts) the:
a. thick filaments shorten.
b. Z lines shorten.
c. thin filaments shorten.
d. interaction of actin and myosin propels the thick and thin filaments past each
other.
2. Which one of the following events is DIRECTLY catalyzed by ATP-binding?
a. Binding of actin to myosin
b. Release of actin-myosin bond
c. The “power stroke” or movement of the myosin filament
3. Look at figure 46.23. Muscle fibers remain in a resting state because:
a. there is insufficient ATP for them to contract
b. binding sites necessary for contraction are blocked by tropomyosin
c. binding sites necessary for contraction are blocked by troponin
d. troponin binds to myosin at rest
4. The function of the T-tubules in muscle is:
a. storage and release of Ca2+.
b. conversion of chemical work to mechanical work.
c. recovery from contraction.
d. communication of the muscle action potential to the Sarcoplasmic reticulum.
5. Was there any material in this pre-reading that you found particularly unclear or
difficult? Were there any parts that were too basic (or that you have covered extensively
before)?