There are no X-ray telescopes on Earth because:
A) they are too expensive to build.
B) no one has yet invented an X-ray telescope that works.
C) we can't figure out how to direct an X-ray beam through space.
D) X-rays don't penetrate Earth's atmosphere.
E) there are no astronomical objects that emit X-rays.
D
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A book is resting on a table. How many forces would be in the free-body diagram of the book?
a. one b. two of the same type c. two of different types d. three or more of the same type e. three or more of at least two different types
Two particles, each having a mass of 3.0 ?g and having equal but opposite charges of magnitude 5.0 nC, are released simultaneously from rest when the two are 5.0 cm apart. What is the speed of either particle at the instant when the two are separated by 2.0 cm?
a. 2.1 m/s b. 1.5 m/s c. 1.8 m/s d. 2.4 m/s e. 3.2 m/s
Long period comets are thought to reside mainly in the:
A) asteroid belt. B) Kirkwood gaps. C) Kuiper Belt. D) Oort Cloud. E) Interstellar Medium.
The speed of a bullet fired from a gun will be about the same as the speed of the recoiling gun
A) when momentum is conserved. B) because velocity is conserved. C) when both velocity and momentum are conserved. D) if the masses of the bullet and gun are equal. E) none of the above