What was the evidence that ancient astronomers used to conclude that Earth did not move?
What will be an ideal response?
Ancient astronomers believed that Earth did not move because they saw no parallax.
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Parallel-Plate Capacitor: Two large closely-spaced parallel metal plates are uniformly and oppositely charged and the electric field between them is 7.6 × 106 N/C.(a) What is the charge per unit area on each plate?(b) If the plates are now moved two times farther apart, what is the electric field between the plates?
What will be an ideal response?
An impact crater that is 10 kilometers across was probably made by the impact of an object about ________ across.
A) 10 meters B) 100 meters C) 1 kilometer D) 10 kilometers E) 100 kilometers
Which of the following statements about black holes is not true?
A) If we watch a clock fall toward a black hole, we will see it tick slower and slower as it falls towards the black hole. B) The event horizon of a black hole represents a boundary from which nothing can escape. C) If you watch someone else fall into a black hole, you will never see him or her cross the event horizon. However, he or she will fade from view as the light he or she emits becomes more and more redshifted. D) If you fell into a supermassive black hole (so that you could survive the tidal forces), you would experience time to be running normally as you plunged across the event horizon. E) If the Sun magically disappeared and was replaced by a black hole of the same mass, the Earth would soon be sucked into the black hole.
Dust particles are pulverized rock, which has density 2500 kg/m3. They are approximately spheres 20 ?m in diameter
Treating dust as an ideal gas, what is the root-mean-square speed (thermal speed) of a dust particle at 400°C? (The Boltzmann constant is 1.38 × 10-23 J/K.) A) 5.2 × 10-5 m/s B) 1.7 × 10-5 m/s C) 3.0 × 10-5 m/s D) 7.3 × 10-5 m/s