A laser produces a beam of 4000-nm light. A shutter allows a pulse of light, 30 ps in duration, to pass.
Which of the following is closest to the uncertainty in the energy of a photon in the pulse? ( h = 1.055 10-34 J s = 6.59 10-16 eV s)
A) 10-3 eV B) 10-6 eV C) 10-4 eV D) 10-2 eV E) 10-5 eV
Question 2
A 25-kg wooden sign 3.0-m long by 2.2-m high is supported by two nails along its left edge, one at the bottom of the sign and the other at the top. The nails are on the same vertical line.
Find the horizontal component of the force exerted by the upper nail. A)
250 N
B)
120 N
C)
360 N
D)
170 N
E)
280 N
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LASIK surgery uses a laser to reshape the cornea.
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