Adrienne (50 kg) and Bo (90 kg) are playing on a 100 kg rigid plank resting on the supports seen in FIGURE 12.33. If Adrienne stands on the left end, can Bo walk all the way to the right end without the plank tipping over? If not, how far can he get past the support on the right?

66. What is the minimum number of slits required in a diﬀraction grating to just resolve light with wavelengths of 471.0nm and 471.6nm A. 99 B. 197 C. 393 D. 786 E. 1179 ans: C 67. X rays are: A. electromagnetic waves B. negatively charged ions C. rapidly moving electrons D. rapidly moving protons E. rapidly moving neutrons ans: A 68. Bragg’s law for x-ray diﬀraction is 2dsinθ = mλ, where θ is the angle between the incident beam and: A. a reﬂecting plane of atoms B. the normal to a reﬂecting plane of atoms C. the scattered beam D. the normal to the scattered beam E. the refracted beam ans: A 69. Bragg’s law for x-ray diﬀraction is 2dsinθ = mλ, where the quantity d is: A. th