Which of the following statements about matter-antimatter engines is not true?
A) One of the major challenges to developing matter-antimatter engines is finding a way to store antimatter after it is produced.
B) Matter-antimatter engines would be great in theory, but to date we have no evidence that antimatter even exists.
C) Matter-antimatter reactions represent the most efficient possible reactions in terms of energy release.
D) Spacecraft powered by matter-antimatter engines could probably reach speeds of more than half the speed of light.
B
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If the amount of polar ice decreases, what would happen, and why?
A) cooling, because melted ice cools things off B) warming, because more sunlight is reflected C) cooling, because more sunlight is reflected D) warming, because more sunlight is absorbed
A tennis ball undergoes an elastic collision when it hits the ground and bounces up. It is given that the speed of the ball just before it hits the ground is –v0 and immediately after rebounding it is +v0. Which of the statements below is true?
A) The momentum of the ball changes but the momentum of Earth does not. B) The momentum of the ball changes and the momentum of Earth also changes by the same amount. C) The momentum of the ball does not change but the momentum of Earth changes. D) Neither the momentum of the ball nor the momentum of Earth changes. E) Additional information is needed to answer this question.
All ________ planets have rings around their equators
Fill in the blank(s) with correct word
Which scientist first suggested that planets move because of some connection between them and the Sun?
a. Copernicus b. Brahe c. Newton d. Kepler e. Galileo