Finding Force in Potential Energy vs. Interatomic Distance graph

In summary, the task is to rank the magnitude of the force at points A, B, and C on a graph of potential energy versus interatomic distance for a molecule. The relevant equation is F = -dU/dx, and the force is attractive when the atoms are far apart and repulsive when they are too close together. The points A, B, and C represent different distances between the atoms, and the task is to determine the slope at these points to find the magnitude of the force.
  • #1
gunster
7
0

Homework Statement



The figure below shows a graph of potential
energy versus interatomic distance for a particular molecule. Rank the magnitude of the
force at locations A, B, and C. (That is, which
is the greatest, which is smallest, and are any
of these equal to each other?)

http://img851.imageshack.us/img851/5526/captureyrd.png [Broken]

Uploaded with ImageShack.us

Homework Equations



F = -dU/dx ?

The Attempt at a Solution



To be honest I really have no idea on this one :/. I thought I could find the force using the change of potential energy corresponding with change in interatomic distance but that does not give me the right answer.

It would seem more logical to calculate force based on R itself. Since it's interatomic, I assume force increased with decreasing R, but again that was wrong.Any ideas?

EDIT: Never mind. I realized my mistake and I did not read the "magnitude" word in the question. I figured out the right answer so this thread is no longer needed
 
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  • #2
You got the relevant equation right. You know that two atoms that might make up a molecule are attracted if they are far apart and if they get too close there is a repulsive force. You also know that that say the two atoms that make up a molecule will find some distance where they like to be separated where you could say the force goes to zero.

You have the points A, B, and C and you what to know the force at those points. From what I wrote and from what you probably know you should be able to come up with answers. What is the slope at points A, B, and C? F = -dU/dx

Good luck!
 

1. What is potential energy?

Potential energy is the energy stored in an object or system due to its position or configuration. It is a form of energy that can be converted into other forms, such as kinetic energy, and is typically measured in joules (J).

2. What is force?

Force is a physical quantity that describes the interaction between two objects or systems. It is a vector quantity, meaning it has both magnitude and direction, and is typically measured in newtons (N). Force can cause an object to accelerate, change direction, or deform.

3. How are potential energy and force related?

Potential energy and force are related through the concept of work. Work is defined as the product of force and displacement, and it is the transfer of energy from one system to another. In a potential energy vs. interatomic distance graph, the force is represented by the slope of the curve, as the derivative of potential energy is force.

4. What does the slope of a potential energy vs. interatomic distance graph represent?

The slope of a potential energy vs. interatomic distance graph represents the force between two atoms at a given distance. A steeper slope indicates a stronger force, while a flatter slope indicates a weaker force.

5. How can a potential energy vs. interatomic distance graph be used in scientific research?

A potential energy vs. interatomic distance graph can be used to study the interactions between atoms and molecules in a system. By analyzing the shape and values of the graph, scientists can determine the stability and behavior of the system, as well as make predictions about how it may react to different conditions. This information is useful in fields such as materials science, chemistry, and physics.

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