A cup that is 6.0 cm tall is in front of a concave lens. The image of the cup is 2.5 cm tall and 7.5 cm from the lens. What is the focal length of the lens?
A) -6.0 cm
B) -7.5 cm
C) -13 cm
D) +18 cm
E) +6.0 cm
C
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A long cylindrical rod, 8 cm in diameter, is initially at a uniform temperature of 20°C. At time t = 0, the rod is exposed to an ambient temperature of 400°C through a heat transfer coefficient of 20 W/(m2 K). The thermal conductivity of the rod is 0.8 W/(mK) and the thermal diffusivity is 3 × 10–6 m2/s. Determine how much time will be required for the temperature change at the centerline of the rod to reach 93.68% of its maximum value. Use an explicit difference equation and compare your numerical results with a chart solution.
GIVEN • Cylindrical rod suddenly exposed to increased ambient temperature FIND (a) Time required for the centerline temperature change to reach 93.68% of its maximum value
Mass on a Spring: A 92-kg man climbs into a car with worn out shock absorbers, and this causes the car to drop down 4.5 cm. As he drives along he hits a bump, which starts the car oscillating at an angular frequency of 4.52 rad/s. What is the mass of the car?
A. 890 kg B. 760 kg C. 920 kg D. 990 kg E. 1900 kg
A jet traveling at 1500 km/h passes overhead. The sonic boom produced is heard by
A) a listener on the ground. B) the jet pilot. C) both of these D) neither of these
The most common rocks on Earth's surface are
a. discordant. b. concordant. c. metamorphic. d. sedimentary.