What is the velocity of a 0.400-kg billiard ball if its wavelength is 7.50 cm (large enough for it to interfere with other billiard balls)?

Video Transcript

This is College Physics Answers with Shaun Dychko. What is the velocity of a 0.400 kilogram billiard ball if it had a de Broglie wavelength of 7.50 centimeters, which is 7.50 times 10 to the minus 2 meters? Well the de Broglie wavelength is Planck's constant divided by the momentum of the billiard ball and momentum is mass times velocity and we can solve this for v by multiplying both sides by v over λ and so we have the velocity of the billiard ball then is Planck's constant divided by the billiard ball mass times its wavelength. So that's 6.626 times 10 to the minus 34 joule seconds divided by 0.400 kilograms times 7.50 times 10 to the minus 2 meters which is 2.21 times 10 to the minus 32 meters per second.