Magnifying Glass With the Image at Infinity: When a person with a near point at 28 cm uses a certain magnifying glass, it produces an angular magnification of 7.0 with the image very distant. What is the focal length of the lens of this magnifying glass?
A. 2.0 cm
B. 3.0 cm
C. 4.0 cm
D. 5.0 cm
E. 6.0 cm
Answer: C
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A bus is designed to draw its power from a rotating flywheel that is brought up to its maximum speed (3000 rpm) by an electric motor. The flywheel is a solid cylinder of mass 250 kg and radius 0.500 m (Icylinder = MR2/2). If the bus requires an average power of 10.0 kW, how long will the flywheel rotate?
a. 154 s c. 463 s b. 308 s d. 617 s
During the eighteenth and nineteenth centuries, attempts to precisely measure the astronomical unit relied largely on rare
A) total solar eclipses. B) transits of the inferior planets across the Sun. C) passages of comets close to the Earth. D) maximum elongations of Venus. E) oppositions of Mars.
An ideal gas is confined to a container with constant volume. The number of moles is constant. By what factor will the pressure change if the absolute temperature triples?
a. 2/3 c. 3 b. 1/3 d. 9
The transit method of planet detection works best for
A) big planets in face-on orbits around small stars. B) big planets in edge-on orbits around small stars. C) Earth-like planets in any orbit. D) small planets in face-on orbits around big stars. E) small planets in edge-on orbits around big stars.