Spherical Mirrors: The focal length of a concave mirror has a magnitude of 20 cm. What is its radius of curvature?
A. 10 cm
B. 40 cm
C. -40 cm
D. 20 cm
E. -20 cm
Answer: B
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If the universe is closed and finite, then
a. the universe will expand forever b. the universe has a center c. the universe has an edge d. none of the above
A 60.0-kg person rides in an elevator while standing on a scale. The scale reads 400 N. The acceleration of the elevator is closest to
A) 3.13 m/s2 downward. B) 6.67 m/s2 downward. C) zero. D) 9.80 m/s2 downward. E) 6.67 m/s2 upward.
Recall that Hubble's law is written v = H0d, where v is the recession velocity of a galaxy located a distance d away from us, and H0 is Hubble's constant. Suppose H0 = 55 km/s/Mpc
How fast would a galaxy located 500 megaparsecs distant be receding from us? Show all work clearly, and state your final answer with a complete sentence. Give the speed in units of kilometers per second and as a percentage of the speed of light.
A large cylindrical water tank is mounted on a platform with its central axis vertical. The water level is 3.75 m above the base of the tank, and base is 6.50 m above the ground. A small hole, 2.22 mm in diameter, has formed in the base of the tank
Both the hole and the top of the tank are open to the air. We can ignore air resistance and treat water as an ideal fluid with a density of 1000 kg/m3. (a) How many cubic meters of water per second is this tank losing? (b) How fast is the water from the hole moving just as it reaches the ground?