# aamc 4r PS Question#63

Discussion in 'MCAT: Medical College Admissions Test' started by da_donut, Aug 10, 2006.

1. ### da_donut Senior Member 2+ Year Member

Joined:
Jul 11, 2006
Messages:
387
0
Hi,

If someone can help me with this question I'd appreciate it. My initial thought when I read the question was that the electron would accelerate to the cathode, but then I started to think about it and got it wrong lol. Here was my reasoning:

F=qE=ma Now my reasoning was that the electric field was constant and so the force doesn't change and thus there is no acceleration. I think i see my problem as I'm writing this....the electric field isn't constant is it...? But why isn't it?

Thanks!

Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
2. ### DrCurious Senior Member 7+ Year Member

Joined:
Jul 16, 2005
Messages:
997
0
You kind of answered your own question. F=qE, if there is a constant force on an object it accelerates. Additionally, the passage states that the cathode is connect to the negative end of the battery so you know it will accelerate away from the cathode.

3. ### Knickerbocker 2+ Year Member

Joined:
Jun 19, 2006
Messages:
1,551
5
Status:
Dental Student
The person above gave a better answer, so I'm removing mine.

4. ### superwillis Senior Member 5+ Year Member

Joined:
May 18, 2006
Messages:
188
0
Remember that a constant force causes acceleration, not a changing one.

Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
5. OP

### da_donut Senior Member 2+ Year Member

Joined:
Jul 11, 2006
Messages:
387
0
Thanks Dr. Curious and Superwillis. This is definately where I made my mistake because I got confused and equated a constant force with 0 acceleration which is incorrect.

Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
6. ### aquila New Member 5+ Year Member

Joined:
Aug 15, 2006
Messages:
74
0
Status:
Pre-Medical
Deleted

We’ve been on the Internet for over 20 years doing just one thing: providing career information for free or at cost. We do this because we believe that the health education process is too expensive and too competitive.

We believe that all students deserve the same access to high quality information. We believe that providing high quality career advice and information ensures that everyone, regardless of income or privilege, has a chance to achieve their dream of being a doctor.