Energy Density: A 4.4 × 1014 Hz laser emits a 2.1 ?s pulse that is 5.0 mm in diameter. The energy density in the beam is 0.24 J/m3. How many wavelengths are there in the length of the beam? (c = 3.0 × 108 m/s, ?0 = 4? × 10-7 T ? m/A, ?0 = 8.85 × 10-12 C2/N ? m2)
A. 9.2 × 108
B. 2.8 × 109
C. 2.8 × 108
D. 9.2 × 109
E. 2.8 × 1010
Answer: A
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For a plane to be able to fly clockwise in a horizontal circle as seen from above, in addition to exerting a force downwards on the air
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Calculate an estimate of the range of a hypothetical force with the proton as the virtual exchange particle. (c = 3.00 × 108 m/s, h = 6.626 × 10-34 J ? s, mproton = 1.67 × 10-27 kg)
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