What is Nonconservative forces: Definition and 23 Discussions

A conservative force is a force with the property that the total work done in moving a particle between two points is independent of the path taken. Equivalently, if a particle travels in a closed loop, the total work done (the sum of the force acting along the path multiplied by the displacement) by a conservative force is zero.A conservative force depends only on the position of the object. If a force is conservative, it is possible to assign a numerical value for the potential at any point and conversely, when an object moves from one location to another, the force changes the potential energy of the object by an amount that does not depend on the path taken, contributing to the mechanical energy and the overall conservation of energy. If the force is not conservative, then defining a scalar potential is not possible, because taking different paths would lead to conflicting potential differences between the start and end points.
Gravitational force is an example of a conservative force, while frictional force is an example of a non-conservative force.
Other examples of conservative forces are: force in elastic spring, electrostatic force between two electric charges, and magnetic force between two magnetic poles. The last two forces are called central forces as they act along the line joining the centres of two charged/magnetized bodies. A central force is conservative if and only if it is spherically symmetric.

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  1. H

    What is the meaning of work done for non-uniform circular motion?

    This is my solution ,and I just use the definition .But I still feel unclear about the concept of non-conservative force.$$ W = F x = 30N (\frac{1}{2}\pi r ) = 56.2 J $$ $$ E_{system} = \Delta K + \Delta U = W $$ $$ (K_{f}- K(i))+(U(f)-U(i)) = W $$ $$ (\frac{1}{2} *m{V_{f}}^2...
  2. ergospherical

    I System, potential energy, and nonconservative forces: The whole story

    [Mentors' note: This thread was split off from https://www.physicsforums.com/threads/system-potential-energy-and-nonconservative-forces.1009237/] This is not a particularly helpful way to think about things; For a general mechanical system, you usually split the specified forces into external...
  3. F

    I System, potential energy, and nonconservative forces

    Hello, I am trying to get my head around the idea of nonconservative forces doing work and changing the potential energy of a system. First of all, forces acting on a system can be: a) internal and conservative b) internal and nonconservative (friction, pushes, pulls, thrust, etc.) c) external...
  4. momoneedsphysicshelp

    Nonconservative Forces Problem with a Model Airplane

    I am sure that the answer will be negative, but I'm not 100% sure on how to solve the problem. My initial answer was -350 J. Please help. Thanks!
  5. F

    Conservative forces, Nonconservative forces and Potential Energy

    Hello, I would like to review and validate some concepts that I have been recently thinking about. Hope this is correct and useful to others that need to refresh these concepts. Forces can be classified as either conservative or nonconservative. Dissipative forces are always nonconservative...
  6. Nikhil Rajagopalan

    Is the Work Done by Static Friction Always Zero in a Round Trip?

    Friction is said to be a non conservative force. And I see various sources state that work done by a non conservative force on a round trip is always non zero. But is that always true? In a case where a coin is placed on a turn table, and the table is rotated, and the coin does not move during...
  7. F

    I Can nonconservative forces change either KE or PE?

    Hello everyone, conservative forces only depend on position (cannot depend on time), i.e. ##F(x)## and are equal to the spatial derivative of the potential energy function ##U(x)##: $$F(x)= - \partial U(x)/\partial x$$ Conservative forces always have to change the kinetic energy KE and...
  8. S

    Is Power only defined for nonconservative forces?

    I am searching for power concept in physics, all I see is the sources give frictional or applied forces for power calculation examples. Frictional or applied forces are nonconservative forces. Why is that so? Is power calculation only valid (or meaningful) for nonconservative systems?
  9. Z

    Force of tension of spring and rope

    why is the tension force of spring conservative and tension force of rope not conservative ??
  10. P

    Block Sliding Down a Ramp that is Free to Slide

    Homework Statement A block with mass m rests on a smooth, frictionless ramp with mass M and height h. The ramp itself sits on a frictionless horizontal surface in which it is free to slide. The block slides smoothly down the ramp from rest. We want to find the speed of the block after it has...
  11. J

    Conceptual question concerning work and nonconservative forces

    Homework Statement Hi all. I feel silly for stumbling on such a simple question, but I can't seem to wrap my head about the conceptual aspect of it. The question is: A box that is initially at rest is pushed by a person at an angle (diagonally downwards), θ, with a force, F, until it reaches...
  12. C

    Nonconservative forces and kinetic/potential energy.

    Homework Statement A 60.0-kg skier starts from rest at the top of a ski slope of height 66.0 m. A) If frictional forces do −1.02×104 J of work on her as she descends, how fast is she going at the bottom of the slope? Answer is 30.9 m/s B)Now moving horizontally, the skier crosses a...
  13. S

    Find the work done by nonconservative forces in stopping the plane.

    Homework Statement Find the work done by nonconservative forces in stopping the plane. A 18000 {\rm kg} airplane lands with a speed of 92 {\rm m/s} on a stationary aircraft carrier deck that is 115 {\rm m} long. Homework Equations W = FD The Attempt at a Solution 18000 * 92 *...
  14. I

    Nonconservative Forces problem

    Homework Statement Suppose that the surfaces described are not frictionless and that the coefficient of kinetic friction between the block and the surfaces is 0.30. The block has an initial speed 7.0m/s and slides 2.0 m before reaching the ramp. Find (a) the speed of the the block when it...
  15. M

    Energy with nonconservative forces

    A 3.0kg slides along a horizontal surface with a speed of 7.0m/s. After sliding a distance of 2.0m, the block makes a transition to a ramp inclined at an angle of 40 degrees to the horizontal. The coefficient of kinetic friction between the block and the surfaces is .30. Find a) the speed...
  16. F

    About the equation for net work done by nonconservative forces

    Wnc = delta (kinetic energy) + delta(potential energy) (Work done by nonconservative forces) = (change in kinetic energy) + (change in potential energy) Now, my professor gave us this formula instead of the one above: W - H = (change in kinetic energy) + (change in potential energy)...
  17. J

    Application with conservative and nonconservative forces

    Homework Statement A 3.0-kg block sliding on a horizontal surface is accelerated by a compressed spring. At first, the block slides without friction. But after leaving the spring, the block travels over a new portion of the surface, with a coefficient of friction 0.20, for a distance of 8.0 m...
  18. L

    Nonconservative forces/ and conservation energy problem

    An 80kg sky diver jump out of a balloon at an altitude of 1000m and opens the parachute at an altitude of 200m.a) assuming that the total retarding force on the diver is constant at 50N with the parachute closed and constant at 3600 with the parachute open, what is the speed of the diver when he...
  19. X

    Diving into water / Nonconservative forces

    Man, I had such an easy time with the subject matter up to this chapter. Any how, I'm stuck agian. :( Here's the trouble this time.
  20. B

    Changes in Mechanical Energy for Nonconservative Forces

    I have a problem for the subject in the title. I'm not really sure where to start, and I can't figure it out. In her hand a softball pitcher swings a ball of mass .250 kg around a vertical circular path of radius 60.0 cm before releasing it from her hand. The pitcher maintains a component...
  21. M

    How do nonconservative forces affect work done in a round trip?

    Hi! I've been needing help with a question in my textbook. It seems so stupidly easy, but I can't get it. (Ironically enough, I understood all the others).. here's the question: A bicyclist rides 5.0km due east, while the resistive foce from the air has a magnitude of 3.0N and points due...
  22. B

    Nonconservative Forces (conceptual)

    I'm having problems with solving these nonconservative forces problems. The teach keeps pointing to Wnc=(KE+PE)f - (KE+PE)i As we use this when there is friction present, I'm totally confused on where the frictional or opposing force is involved when solving. I've basically been ignoring the...
  23. I

    Why Does a Car Speed Up on a Sloped Driveway Despite Friction?

    I am really having a hard time with this there is something I am missing can someone help a 2100 kg car starts from rest at the top of a 5.0 m long driveway that is sloped at 20 Deg with the horizontal . if an average friction force of 4000 N impedes the motion find the speed of the car at the...