On the scale of the cosmic calendar, in which the history of the universe is compressed to 1 year, how long has human civilization (i.e., since ancient Egypt) existed?
A) about half the year
B) about a month
C) a few hours
D) a few seconds
E) less than a millionth of a second
D) a few seconds
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A nonprismatic cantilever bar has an internal cylindrical hole of diameter d/2 from 0 to x, so the net area of the cross section for Segment 1 is (3/4)A. Load P is applied at x, and load 2P/2 is applied at x 5 L. Assume that E is constant. The length of the hollow segment, x, required to obtain axial displacement ? 5 PL/EA at the free end is:
(A) x 5 L/5
(B) x 5 L/4
(C) x 5 L/3
(D) x 5 3L/5
On page 526 of your textbook, you learned that one gram of radium produces over a million times the radiation as does one gram of uranium. This means that a much larger fraction of radium atoms are undergoing radioactive decay each second than for uranium. How does the half-life of radium compare to the half-life of uranium?
a. The half-life of radium is much smaller than the half-life of uranium. b. The half-life of radium is the same as the half-life of uranium. c. The half-life of radium is much larger than the half-life of uranium. d. The information is insufficient to answer the question. e. The half-life of the radium is shorter at first, but gets longer as the radium sample is depleted.
An earthquake generates three kinds of waves: surface waves (L-waves), which are the slowest and weakest, shear (S) waves, which are transverse waves and carry most of the energy, and pressure (P) waves, which are longitudinal waves and are the
fastest. The speed of P waves is approximately 7 km/s, and that of S waves is about 4 km/s. People do not generally feel the P waves, but animals seem to be sensitive to them. If a person reports that her dog started barking 20 seconds "before the earthquake," then approximately how far was the origin of the earthquake? A) 100 km B) 200 km C) 300 km D) 400 km E) 500 km
Our home galaxy is called the ______________
Fill in the blank(s) with correct word