The human eye can just detect green light of wavelength 500 nm if it arrives at the retina at the rate of 2 × 10-18 W
How many photons arrive each second? (c = 3.0 × 108 m/s, h = 6.626 × 10-34 J ? s)
5
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A very small 100-g object is attached to one end of a massless 10-cm rod that is pivoted without friction about the opposite end. The rod is held vertical, with the object at the top, and released, allowing the rod to swing
What is the speed of the object at the instant that the rod is horizontal? A) 0.71 m/s B) 4.0 m/s C) 1.4 m/s D) 2.8 m/s E) 2.8 m/s
A seed is 15 mm in front of a converging lens, and the image of the seed is 4.0 mm behind the lens. What is the focal length of the lens?
A) 11 mm B) 5.5 mm C) 3.8 mm D) 3.2 mm
A pendulum is made with a 4.00 kg mass suspended at the end of a 75.0 cm thin rod. The period of the small motion simple harmonic motion is
A. 2.45 sec. B. 2.01 sec. C. 1.74 sec. D. 1.33 sec. E. 1.04 sec.
In order to simulate weightlessness for astronauts in training, they are flown in a vertical circle. If the passengers are to experience weightlessness, how fast should an airplane be moving at the top of a vertical circle with a radius of 2.50 km?
A) 157 m/s B) 314 m/s C) 78.5 m/s D) 255 m/s E) 510 m/s