A 8-kg object moves up vertically a distance of 3 m. Its potential energy has changed by approximately how much?
a. It has increased by 24 J.
b. It has decreased by 240 J.
c. It has decreased by 24 J.
d. It has increased by 240 J.
Answer: a. It has increased by 24 J.
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A. 93 J B. 186 J C. 47 J D. 121 J
Which of the following correctly describes the relationship between Newton's theory of gravity and general relativity?
A) Newton's theory of gravity is an approximation to general relativity that works when gravity is relatively weak but breaks down when gravity is strong. B) Newton's theory of gravity is now known to be false, and we were previously misled to think it was true by measurement errors. C) Newton's theory of gravity and general relativity give the same answers, but the former tells us to think of gravity as a force and the latter tells us to think of gravity as curvature of spacetime. D) General relativity applies at the subatomic level, but Newton's theory of gravity does not.
Sound waves can interfere with one another so that no sound results
A) True B) False C) Either, depending on the air temperature.
Which of the following is a unit of power?
a. Btu b. kilowatt c. kilowatt-hour d. joule e. horsepower per hour