A concave mirror has an object placed 40 cm in front of it. An image forms 60 cm in front of the mirror. What is the focal length of the mirror?
A. 60 cm
B. 120 cm
C. -120 cm
D. 100 cm
E. 24 cm
E. 24 cm
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Which of the following is a difference between low-mass stars and medium-mass stars?
A) Unlike medium-mass stars, low-mass stars can ignite hydrogen and helium. B) Unlike medium-mass stars, low-mass stars develop an inert helium core surrounded by unprocessed hydrogen. C) Unlike medium-mass stars, low-mass stars are not completely convective. D) Unlike medium-mass stars, low-mass stars cannot become giant stars.
Identical forces are exerted for the same length of time on two different objects. The magnitude of the change in momentum of the lighter object is
A) smaller than the magnitude of the change in momentum of the larger mass object, but not zero. B) larger than the magnitude of the change in momentum of the larger mass object. C) exactly equal to the magnitude of the change in momentum of the larger mass object. D) zero. E) There is not enough information to answer the question.
In the vicinity of what frequency does an object with a temperature of 1000 K radiate the largest amount of power? (c = 3.00 × 108 m/s,
Wien displacement law constant equals 2.90 × 10-3 m ? K, ? = 5.670 × 10-8 W/m2 ? K4) A) 1.0 × 1014 Hz B) 8.0 × 1014 Hz C) 2.3 × 1014 Hz D) 6.7 × 1014 Hz E) 4.1 × 1014 Hz
When water freezes, the surrounding air is
1) cooled, 2) warmed, 3) unchanged, and when ice melts, the surrounding air is 4) cooled. 5) warmed. 6) unchanged.