Conservative Force: Is F Dependent on Velocity?

In summary: Force_fields.Velocity dependent forces are generally not conservative and exception is the Lorentz force due to a magnetic field acting on a charged particle although some would strictly speaking not consider this force conservative either.
  • #1
johann1301
217
1
If F is a force acting on a atom and is dependent on the velocity of the atom. Is the force conservative?
 
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  • #2
What do you think -- what is the definition of a conservative force?
 
  • #3
Velocity dependent forces are generally not conservative and exception is the Lorentz force due to a magnetic field acting on a charged particle although some would strictly speaking not consider this force conservative either.
 
  • #4
Lets say

F=-av

If i integrate this, isn't it soley dependent on the start and end point? And thus, its conservative..?
 
  • #5
a is just a constant.
 
  • #6
V is dependent of time since v = a*t = m*a. Isn't it clear therefore that the work in reaching a specific position will depend on the path traveled. The longer the path the more time and thus more work.
 
  • #7
my a is the acceleration due to the force
 
  • #8
johann1301 said:
Lets say

F=-av

If i integrate this, isn't it soley dependent on the start and end point? And thus, its conservative..?
Certainly not. Consider ##a=-1 \; N/(m/s)## and an object which goes out a distance of 1 m at 1 m/s and then back at 1 m/s and another which goes out the same 1 m distance at 1 m/s and then back at 10 m/s. The force does 2 J of work for the first path and 11 J of work for the second. Furthermore, the work is non-zero, so both differ from the path which just stays at the endpoints.
 
  • #9
gleem said:
Velocity dependent forces are generally not conservative and exception is the Lorentz force

... or any other force always acting perpendicular to velocity (e.g. coriolis force).
 
  • #10
Are you asking if force is always conserved? From my understanding yes f=mv thus it will always equation out to your mass and velocity on the other side of the equals sign?
 
  • #11
audire said:
Are you asking if force is always conserved? From my understanding yes f=mv thus it will always equation out to your mass and velocity on the other side of the equals sign?
That is not at all what is being asked.

A force is "conservative" if the work done on an object by that force as it moves along any path that loops back to where it started is always equal to zero. Note that in this context we are talking about a force "field" as in http://en.wikipedia.org/wiki/Field_(physics)
 

1. What is a conservative force?

A conservative force is a type of force that does not depend on the path taken by an object and only relies on the initial and final positions of the object. This means that the work done by a conservative force is independent of the path taken and only depends on the end points.

2. What are some examples of conservative forces?

Some examples of conservative forces include gravitational force, elastic force, and electrostatic force. These forces all follow the principle of being independent of the path taken and only relying on the initial and final positions of the object.

3. How is a conservative force related to potential energy?

Conservative forces are related to potential energy through the concept of work. Since the work done by a conservative force is independent of the path taken, the change in potential energy (or the energy stored in an object due to its position) is also independent of the path taken.

4. Is the force dependent on velocity in a conservative system?

No, in a conservative system, the force is not dependent on velocity. This means that the magnitude and direction of the force remain constant regardless of the object's velocity. This is because the work done by a conservative force is solely dependent on position and not on any other factors like velocity or time.

5. How do conservative forces affect an object's motion?

Since conservative forces do not depend on the path taken, they do not dissipate energy or cause any change in an object's kinetic energy. This means that in a closed system (where there are no external non-conservative forces acting), the total mechanical energy (kinetic energy + potential energy) remains constant. Therefore, conservative forces do not affect an object's motion in terms of speed, but instead, they can change its direction of motion.

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