We live in the period called the
a. Cenozoic.
b. Holocene.
c. Ordovician.
d. Quaternary.
d
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Global temperature variations on Earth driven by the Milankovitch cycle differ from those driven by the anthropogenic greenhouse effect in that
a. they are very small in magnitude, less than 1°C. b. they occur at irregular time intervals. c. they are driven by volcanic activity. d. they occur over much longer time scales (thousands of years). e. they are driven by emissions of methane gas rather than carbon dioxide.
This figure depicts pollen grains suspended in a liquid exhibiting a continual, erratic motion known as Brownian motion. Albert Einstein inferred that atoms exist based on his calculations that described this type of motion. What was the basis for his conclusion?
a. The erratic motions of the pollen grains were explained by Einstein to result from random collisions with water molecules. b. The tiny grains could be shown to be atoms. c. The existence of atoms was an inescapable conclusion of his theory of relativity. d. The existence of atoms was an inescapable conclusion of his theory of the photoelectric effect. e. The existence of atoms was an inescapable conclusion of his theory of heat capacities of solids.
Derive an equation of the form hc = f(T, D, U) for turbulent flow of water through a long tube in the temperature range between 20° and 100°C.
GIVEN
• Turbulent water flow through a long tube
• Water temperature range (Tb) = 20°C to 100°C FIND
• An expression of the form h c= f(T, D, U)
ASSUMPTIONS
• Steady state
• Variation of properties with temperature can be approximated with a power law
• Fully developed flow
• Water is being heated
SKETCH
PROPERTIES AND CONSTANTS
for water
A boy throws a rock with an initial velocity of at 30.0° above the horizontal. How long does it take for the rock to reach the maximum height of its trajectory if air resistance is negligibly small and g = 9.80 m/s2?
A) 0.160 s B) 0.282 s C) 0.313 s D) 0.441 s