# De Broglie wavelength of a tennis ball

1. Dec 8, 2014

### Davidmb19

This is a multiple choice question.
The de Broglie wavelength of a moving tennis ball is calculated as 1x10^-33. This means that the moving tennis ball
A)Diffracts through a narrow slit.
B)Does not behave as a particle
C)Does not display wave properties
D)Is travelling at the speed of light

The answer is C and I know this through the process of elimination however, I do not conceptually understand why it is. Can someone please explain?

2. Dec 8, 2014

### Bystander

What's the momentum?

3. Dec 8, 2014

### Davidmb19

Wavelength= Plank's constant/Momentum
Therefore rearranging the equation
(6.63x10^-34)/(1x10^-33)=0.663

4. Dec 8, 2014

### Bystander

... and, the mass of a tennis ball?

5. Dec 8, 2014

### Davidmb19

lol We don't know the mass. This is a multiple choice but the mass of a tennis ball, in general, is about 58 grams.

6. Dec 8, 2014

### Bystander

With that mass is it anywhere near light speed?

7. Dec 8, 2014

### Davidmb19

Ahhhh I see! I didn't think of that. Thank you :).

8. Dec 8, 2014

### Bystander

Good --- that take care of things for you?

9. Dec 8, 2014

### Davidmb19

Yep. Thanks :D