As a body falls through air starting from rest, its velocity
a. stays constant
b. continuously decreases
c. continuously increases
d. gets larger and larger, eventually reaching a constant value
e. gets smaller and smaller, eventually approaching zero
D
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Which surface feature of the Moon is NOT found on Mercury?
A. craters B. rays C. maria D. mountains
A metal rod of length L in a region of space where a constant magnetic field points into the page rotates clockwise about an axis through its center at constant angular velocity ?. While it rotates, the point(s) at highest potential is(are)
a.
A.
b.
B.
c.
C.
d.
D.
e.
A and E.
Your company has developed a new polymer, and you are asked to determine
(a) its elastic modulus and (b) its viscosity. To measure these properties, you choose to conduct a stress-relaxation test at 300 K. At 300 K a specimen of the new polymer is strained at t=0 by an amount of 3×10-3, and this requires an initial stress of 6×106 Pa. This strain is constant for 100 hours, and the stress on the polymer has dropped to 3×106 Pa. Assume that this polymer can be modeled as a Maxwell solid, with the viscous component behaving as a Newtonian fluid.
The temperature of a 100 m diameter cooling pond is 7°C on a winter day. If the air temperature suddenly drops to –7°C, calculate the thickness of ice formed after three hours.
GIVEN
? A round cooling pond on a winter day
? Initial temperature (Tl) = 7°C
? Air temperature (T?) drops to –7°C
? Pond diameter (D) = 100 m
FIND
? The thickness of ice (?) formed after 3 hours
ASSUMPTIONS
? The thermal capacitance of the ice layer is negligible
? Radiative heat transfer is negligible
? Bulk water temperature remains constant at 7°C
? Air temperature is constant at –7°C
? The air and water are still
SKETCH
PROPERTIES AND CONSTANTS
The ice property values given in the problem statement of Problem 9.37 is
Extrapolating from Appendix 2, Table 28, for dry air at the estimated film temperature of –3.5°C
From Appendix 2, Table 13, for water at the estimated film temperature of 3.5°C
