You would like to see through the dust in a cloud to find protostars. Which band of the electromagnetic spectrum would you need to look in?
a. infrared b. visual
c. UV d. X-ray
a
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Thin Lenses: Which statement about a single thin lens is correct?
A. A converging lens always produces a real inverted image. B. A diverging lens always produces a virtual inverted image. C. A converging lens sometimes produces a real upright image. D. A diverging lens always produces a virtual upright image. E. A diverging lens produces a virtual upright image only if the object is located between the lens and its focal point.
The first step in the proton-proton chain produces an antielectron, or positron. What happens to the positron?
A) It slowly works its way to the Sun's surface, where it escapes into space. B) It rapidly escapes from the Sun, traveling into space at nearly the speed of light. C) It almost immediately annihilates with an electron, resulting in two gamma-ray photons. D) It quickly meets an ordinary electron, forming an electron-positron pair that remains stable. E) It joins with a nearby neutron to form a proton.
One of the intriguing questions for scientists of many ages has been "What are the elementary particles?" Which of the following is not considered an elementary particle?
A. Electron B. Quark C. Proton D. Muon
A ceiling fan is turned on and reaches an angular speed of 120 rev/min in 20 s. It is then turned off and coasts to a stop in an additional 60 s. The ratio of the average angular acceleration for the first 20 s to that for the last 60 s is which of the following?
a. 3 c. 0.3 b. –3 d. –0.3