A flashlight bulb typically has a small metallic button at one end, and this button is surrounded by ceramic material. The chief purpose of the ceramic material is to
A. provide a conducting path to the filament.
B. insulate the metal button from the other contact point.
C. shut the filament off if the current gets too high.
D. provide extra mass at the bottom of the bulb.
Answer: B
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The Oort Cloud is thought to be
A) the cloud of gas and dust from which our solar system formed. B) a cloud of debris that occasionally encounters the Earth, causing a meteor shower. C) the spherical cloud of comets and some larger icy bodies surrounding the outer solar system. D) a cloud of asteroids moving between the orbits of Mars and Jupiter. E) the material in the ecliptic plane that creates the zodiacal light.
An object is placed 100 cm in front of a lens of focal length 20 cm. A second lens is placed 15 cm past the first lens. The second lens has a focal length of 40 cm. Where is the final image formed?
A) 25 cm in front of the second lens B) 8 cm in front of the second lens C) 8 cm after the second lens D) 10 cm after the second lens E) 25 cm after the second lens
Two objects of different mass are released simultaneously from the top of a 20-m tower and fall to the ground. If air resistance is negligible, which statement best applies?
a. The greater mass hits the ground first. b. Both objects hit the ground at the same time. c. The smaller mass hits the ground first. d. No conclusion can be made with the information given.
A racquetball strikes a wall with a speed of 30 m/s and rebounds in the opposite direction with a speed of 26 m/s. The collision takes 20 ms. What is the average acceleration of the ball during the collision with the wall?
A) 200 m/s2 B) 1300 m/s2 C) 1500 m/s2 D) 2800 m/s2 E) 0 m/s2