Which of the following best explains why we can rule out the idea that planets are usually formed by near-collisions between stars?
A) Studies of the trajectories of nearby stars relative to the Sun show that the Sun is not in danger of a near-collision with any of them.
B) Stellar near-collisions are far too rare to explain all the planets now known to orbit nearby stars.
C) A near collision might have created planets, but it could not have created moons, asteroids, or comets.
D) A near collision should have left a trail of gas extending out behind the Sun, and we see no evidence of such a trail.
B
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Energy Density: The maximum magnetic energy density of a sinusoidal electromagnetic wave is 8.95 × 10-5 J/m3. What is the amplitude of the magnetic field component of this wave? (c = 3.00 × 108 m/s, ?0 = 4? × 10-7 T ? m/A, ?0 = 8.85 × 10-12 C2/N ? m2)
A. 12.0 ?T B. 13.0 ?T C. 14.0 ?T D. 15.0 ?T E. 16.0 ?T
In an elastic collision between two bodies of mass m1 and m2, with m2 initially at rest, mass 1 moves off at angle ? relative to the direction of its initial velocity and mass 2 at angle ?. An exam paper shows the equations below: m1v1i0 = m1v1f cos? + m2v2f sin?= m1v1f sin? + m2v2f cos?What error(s) has the student made?
A. In the first equation, m2v2f sin? should be m2v2f cos?. B. In the second equation, m2v2f cos? should be m2v2f sin?. C. In the second equation, the plus sign between the terms on the right should be a minus sign. D. All of the errors listed above. E. Only errors (a) and (b) above.
Alumina (Al2O3) is a(n) ______________material.
Fill in the blank(s) with the appropriate word(s).
Constructive interference is a result of two waves arriving at a point ________.
Fill in the blank(s) with the appropriate word(s).