You decide to roll a 0.15-kg ball across the floor so slowly that it will have a small momentum and a large de Broglie wavelength. A. If you roll it at 1.1×10 ?3 m/s , what is its wavelength? Express your answer to two significant figures and include the appropriate units. B. How does this compare with the de Broglie wavelength of the high-speed electron that strikes the back face of one of the early models of a TV screen at 1/10 the speed of light (2.4×10?11m)? Express your answer using two significant figures. Solution A) p = mv = 0.15 kg × .0011 m/s = 1.65×10 -4 kg m/s Thus, wavelength lambda = h/p = (6.6 × 10 -34 Js) / (1.65×10 -4 kg m/s)= 4.0 × 10 -30 m B) (4 × 10 -30 m) / (2.4 × 10 -11 m) = 1.7 × 10 -19 .

1. You decide to roll a 0.15-kg ball across the floor so slowly that it will have a small momentum
and a large de Broglie wavelength.
A. If you roll it at 1.1×10 ?3
m/s , what is its wavelength?
Express your answer to two significant figures and include the appropriate units.
B. How does this compare with the de Broglie wavelength of the high-speed electron that strikes
the back face of one of the early models of a TV screen at 1/10 the speed of light (2.4×
10?11m)?
Express your answer using two significant figures.
Solution
A)
p = mv = 0.15 kg × .0011 m/s = 1.65×10 -4
kg m/s
Thus, wavelength lambda = h/p = (6.6 × 10 -34
Js) / (1.65×10 -4
kg m/s)= 4.0 × 10 -30 m
B)
(4 × 10 -30
m) / (2.4 × 10 -11
m) = 1.7 × 10 -19