# surface tension- flatten or spherical

Discussion in 'MCAT Study Question Q&A' started by km1865, Jul 27, 2011.

1. ### km1865 7+ Year Member

Joined:
Nov 9, 2010
Messages:
97
0
Status:
Pre-Medical
Quick question, TBR mentions that in the presence of a gravitational field, surface tension tends to flatten fluid surfaces, this is decreasing the surface area correct? But it also states that when gravity is weak/absent the surface area will be shrunk by forming a sphere. So if I understand correctly, then the overal outcome of this phenomenon is to decrease surface area since the net forces acting on a surface molecule tend to pull it into the liquid right...

Now, theres a question in the book that has me a little confused. It reads: increasing the surface tension of a cell surface will: The correct answer is make the shape more spherical. I understand that this decreases the surface area of the cell, but another answer choice which is NOT the correct answer is make the cell flatten. Can someone explain why the cell would NOT flatten and WOULD become spherical if surface tension was increased?

Thanks so much!

2. ### TieuBachHo 7+ Year Member

Joined:
Jul 23, 2008
Messages:
212
0
You might be confusing about the surface area vs. surface tension. The overall phenomenon is to relieve the surface tension; thereby it maintains the stability of fluids. The liquid tends to resist extenal forces that act to decrease its stability. Don't be fixated on surface area because it varies with external forces.

When you increase the surface area of the cell? What would that do to the cell? It creates stress on the cell right? Thereby, the cell will act against this stress to become more spherical so to achieve its natural low energy state. If you flatten the cell, you create stress on the cell and this is the external force acting on the cell; thereby, it causes the cell to become more spherical as a RESULT. Make sense?

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.