An amateur astronomer grinds a double convex lens whose surfaces have radii of curvature of 40 cm and 60 cm. The glass has an index of refraction of 1.54. What is the focal length of this lens in air?
A) 42.5 cm
B) 126 cm
C) 88.8 cm
D) 44.4 cm
E) 222 cm
D
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A mass 
is connected by a light string that passes over a pulley of mass M to a mass 
as shown in the figure. Both masses move vertically and there is no slippage between the string and the pulley. The pulley has a radius of 30.0 cm and a moment of inertia of 
If 
is 4.00 kg, 
is 3.00 kg and M is 6.00 kg, then what is the acceleration of the masses?
A. 0.695 
B. 0.703
C. 0.731
D. 0.754
E. 0.805
If the temperature of an ideal gas is increased from 20°C to 40°C, by what percent does the speed of the molecules increase?
A) 3% B) 30% C) 70% D) 100%
A telescope is used to view two small lights separated by 2.0 cm at a distance of 500 m. What minimum objective lens diameter is needed to just resolve these objects if their wavelength is 656 nm?
a. 2.0 cm b. 1.0 cm c. 1.2 cm d. 2.4 cm
A huge explosion is heard 20 miles away. How long does it take the sound to travel that far? (20 miles = 32,000 meters)