## Who likes Apple Pie?

• Imagine you are sipping tea or coffee while discussing various issues with a broad and diverse network of students, colleagues, and friends brought together by the common bond of physics, graduate school, and the physics GRE.

WhoaNonstop
Posts: 853
Joined: Mon Sep 21, 2009 1:31 am

### Who likes Apple Pie?

If Jimmy can eat a whole apple pie in 24 minutes and Susie can eat a whole apple pie in 36 minutes, how long will it take to eat a single pie if it is shared by Jimmy and Susie?

-Riley

CarlBrannen
Posts: 381
Joined: Mon May 24, 2010 11:34 pm

### Re: Who likes Apple Pie?

Use units of s = 6 minutes. Jimmy eats at a rate of 1/4 pie/s, Susie at 1/6 pie/s. So sum them to get 3/12 + 2/12 = 5/12.

Answer is 12/5 s = 12*6/5 minutes = 14.4 minutes.

HappyQuark
Posts: 762
Joined: Thu Apr 16, 2009 2:08 am

### Re: Who likes Apple Pie?

WhoaNonstop wrote:If Jimmy can eat a whole apple pie in 24 minutes and Susie can eat a whole apple pie in 36 minutes, how long will it take to eat a single pie if it is shared by Jimmy and Susie?

-Riley

Oh, that's a tough one. Could you rephrase the question in terms of gamma and beta emission half-lives? I do much better with physics than pie.

WhoaNonstop
Posts: 853
Joined: Mon Sep 21, 2009 1:31 am

### Re: Who likes Apple Pie?

I wonder if they'd ever put anything about apple pie on the Physics GRE?

-Riley

kroner
Posts: 218
Joined: Fri Sep 25, 2009 1:58 am

### Re: Who likes Apple Pie?

I believe the answer is 18 min, because Susie threatens to stab Jimmy with the pie knife when he moves to eat part of her half of the pie just after the 12 min mark.

WhoaNonstop
Posts: 853
Joined: Mon Sep 21, 2009 1:31 am

### Re: Who likes Apple Pie?

kroner wrote:I believe the answer is 18 min, because Susie threatens to stab Jimmy with the pie knife when he moves to eat part of her half of the pie just after the 12 min mark.

Correct. Maybe we should translate this problem into Beta and Gamma decays, which won't fight over pie.

-Riley

HappyQuark
Posts: 762
Joined: Thu Apr 16, 2009 2:08 am

### Re: Who likes Apple Pie?

WhoaNonstop wrote:
kroner wrote:I believe the answer is 18 min, because Susie threatens to stab Jimmy with the pie knife when he moves to eat part of her half of the pie just after the 12 min mark.

Correct. Maybe we should translate this problem into Beta and Gamma decays, which won't fight over pie.

-Riley

In which universe do Beta and Gamma decays not fight over pie? Not ours, I can assure you.