Two cars collide head-on on a level friction-free road. The collision was completely inelastic and both cars quickly came to rest during the collision. What is true about the velocity of this system's center of mass?
A) It was always zero.
B) It was never zero.
C) It was not initially zero, but ended up zero.
A
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Which of the following statements best describes what is "relative" in the theory of relativity?
A) The theory says that everything is relative. B) The theory says that truth can never be established in any absolute sense. C) The theory says that measurements of motion make sense only when we state what they are measured relative to. D) The theory says that the speed of light is relative and depends on who is measuring it. E) The theory says that all scientific results must be considered within the context of the scientists' individual viewpoints.
What, if any, evidence did Galileo have for the law of inertia?
A) A smooth ball slows down when rolling uphill, and speeds up when rolling downhill, so it should maintain an unchanging speed on a level surface. B) Using a telescope, he observed meteors and comets moving at unchanging velocity through outer space. C) Noting that the length of the year does not change, he concluded that Earth must maintain an unchanging speed when moving around the sun. D) All of the above. E) He didn't have direct evidence, but proposed the law of inertia only because of the known failures of Aristotelian physics.
Europa is covered with an ocean of ________
Fill in the blank(s) with correct word
Find the frequency of X-rays of wavelength 1 Å = 10?10 m
a. 3 × 10^18 Hz b. 3 × 10^10 MHz c. 6 × 10^9 Hz d. 3 × 10^8 Hz e. 3 × 10^20 Hz