Work-Energy Theorem: A driver, traveling at 22 m/s, slows down her 2000 kg truck to stop for a red light. What work is done on the truck by the friction force of the road?
A. -2.2 × 104 J
B. -4.4 × 104 J
C. -4.8 × 105 J
D. -9.7 × 105 J
Answer: C
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Magnetic Field of a Current Loop: What is the strength of the magnetic field at the center of a circular loop of wire of diameter 8.0 cm when a current of 2.0 A flows in the wire? (?0 = 4? × 10-7 T ? m/A)
Fill in the blank(s) with the appropriate word(s).
If a convex lens were made out of very thin clear plastic filled with air, and were then placed underwater where n = 1.33 and where the lens would have an effective index of refraction n = 1, the lens would act in the same way
A. as a concave mirror in air. B. as a concave lens in air. C. as a convex lens in air. D. as a flat refracting surface between water and air as seen from the water side. E. as the glasses worn by a farsighted person.
In the figure below, a hoop (radius R = 1.0 m, mass = 2.0 kg) having four spokes of negligible mass is suspended from a pivot a distance d = .25 m above its center of mass. The angular frequency (in rad/s) for small oscillations is approximately
?
?
A. 4.0. B. 2.5. C. 1.5. D. 1.0. E. 0.5.
At a certain time, the average size of a transistor in a microprocessor was 250 nanometers. A human hair has a diameter of 70 microns (micrometers). How many transistors fit across a human hair?
A) 280 B) 28 C) 2800 D) 2.8 E) 0.28