What evidence do we have that Earth has a molten core?
What will be an ideal response?
Earthquakes produce vibrations called seismic waves that travel through the crust and interior. Pressure (P) waves travel as a series of compressions and uncompressions, and can pass through a liquid. Shear (S) waves travel as a type of side-to-side vibration that can't pass through a liquid. When an earthquake occurs, no direct S waves pass through the core to register on seismographs on the opposite side of Earth. The absence of S waves shows that the core is mostly liquid, and the size of the S-wave shadow shows that the outer boundary of the core lies slightly more than halfway between Earth's center and surface.
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If we went back in time 10 billion years, how would we expect a plot of galaxy luminosities against colors to change?
A) The red cloud would be much more sparse. B) The blue cloud would be much more heavily populated. C) The blue cloud would be much less populated. D) Both A and B
The site from which an airplane takes off is the origin. The x axis points east; the y axis points straight up. The position and velocity vectors of the plane at a later time are given by
?
.
?
The magnitude, in meters, of the plane's displacement from the origin is
A. 9.14 × 103. B. 1.61 × 104. C. 1.84 × 104. D. 9.14 × 103t. E. 1.61 × 104t.
If the vectors 
and 
have magnitudes of 10 and 11, respectively, and the scalar product of these two vectors is ?100, what is the magnitude of the sum of these two vectors?
A. 6.6 B. 4.6 C. 8.3 D. 9.8 E. 7.6
Peak values for a neodymium-glass laser are 600 J for 1.00 nanosecond. If the cross-section of the laser beam is 1.10 cm2, what are the maximum values of E and B? (µ0 = 4? × 10^?7 T?m/A, c = 3.00 × 10^8 m/s)
a. 2.0E+9 V/m, 1.9 T b. 5.7E+8 V/m, 6.8 T c. 2.0E+9 V/m, 6.8 T d. 5.7E+8 V/m, 1.9 T e. Not enough information.