Through a bizarre (and scientifically unexplainable) fluctuation in the spacetime continuum, a copy of a book titled Iguoonos: How We Evolved appears on your desk
As you begin to read, you learn that the book describes the evolution of the people living in the star system described above. In the first chapter, you learn that these people evolved from organisms that lived 5 billion years ago. Which of the following statements should you expect to find as you continue to read this book? A) As a result of traumatic experiences of their evolutionary ancestors, they dislike television.
B) Their immediate ancestors were chimpanzees.
C) They found that the presence of two stars in their system was critical to their evolution.
D) They evolved on a different planet in a different star system and moved to their current location.
E) They evolved from primitive wormlike creatures that had 13 legs, 4 eyes, and bald heads, thus explaining why such critters are now considered a spectacular delicacy.
D
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Suppose the date is June 21 and the Sun never sets, just touching your northern horizon at midnight. Where are you?
A) the equator B) the Tropic of Cancer C) the Tropic of Capricorn D) the Arctic Circle E) the Antarctic Circle
Consider a heat treatment process in which steel rods with a 10 cm diameter at an initial temperature of 600°C are inserted into an oil bath at 25°C. Assuming a convection coefficient of 400 W/(m2 K) between the oil and the rod, estimate how long it takes for the centerline of the rod to cool to 60°C. If the steel rod, which is 1 m long, is withdrawn from the bath at this point in the process, i.e., when the centerline temperature has reached 60°C, estimate the rate at which heat must be extracted from the oil to maintain its temperature constant during the process of treating 25 rods per hour.
GIVEN
• Heat treatment of steel rod inserted in oil bath
• Rod outside diameter = 0.1 m
• Initial temperature (T0) = 600°C
• Oil bath temperature (T?) = 25°C
• The average heat transfer coefficient ch = 400 W/(m2 K)
FIND
• Time it takes for centerline of the rod to cool to 600C.
• Rate at which heat must be extracted from oil to maintain its temperature constant during the process of treating 25 rods per hour.
ASSUMPTIONS
• Radial conduction only in billet
• Uniform and constant properties
SKETCH
In science fiction movies, spaceships are often shown dodging through large numbers of closely spaced, boulder-size objects. Which of the following real things in our solar system would look most like such science fiction dangers?
A) the rings of Saturn B) the asteroid belt C) the Oort cloud D) the atmosphere of Jupiter
The period of an oscillating weight on a spring in an inertial frame of reference is 2.5 s. What would be its speed if it were to move by an observer who measures its period as 3.4 s? (c = 3.00 × 10^8 m/s)
a. 1.5 × l08 m/s b. 2.0 × 10^8 m/s c. 2.8 × l08 m/s d. 6.8 × 10^7 m/s e. 1.3 × 10^8 m/s