Conservative force is the force required to move a particle from one point to another irrespective of the nature of the path taken by it. The word conservative implies that a conservative force follows the law of conservation of energy; therefore, the total energy remains conserved or preserved in the reference frame. It depends only on the initial and final position of the object. The work done by a conservative force is reversible in nature. If the path followed by a particle has the same initial and final point, i.e., if the particle moves in a closed path, then the work done by a conservative force is equal to zero.
Examples of Conservative Force
1. Weight of an Object
The gravitational force acting on an object pulls it towards the center of the earth and is responsible to compute its weight. The weight of the object does not depend on the path taken by it while moving. The force of gravity only depends upon the position of the object. Hence, the weight of an object is one of the prime examples of a conservative force.
2. Stretching an Elastic Band
Stretching an elastic or a rubber band involves applying a pull force across both ends of the band. This mechanical force deforms the original structure of the band temporarily. The original shape of the band gets restored as soon as the force is removed. This means that the energy possessed by the band remains conserved. Hence, an elastic force can be listed under the category of a conservative force.
3. Poles of a Magnet
A magnet consists of two poles, namely a north pole and a south pole. The imaginary field lines developed due to the magnetic field emerge out of the North Pole and end at the South Pole. A ferromagnetic or a paramagnetic element placed in the magnetic field experiences a force of attraction or repulsion accordingly. The magnetic force depends on the position of the object/position of the objects. In this case, the path followed by an object is not considered, and hence it is known as a conservative force
4. Charged Comb
After combing, a comb develops a charge on its teeth. When this charged comb is deliberately bought near small bits of paper, they tend to get attracted towards the comb. The work done by the electrostatic force to pull the paper particles towards the charged body can be reversed easily. Hence, an electrostatic force is conservative in nature.
5. Objects Falling on the Ground
An object falls on the ground because of the gravitational pull of the earth. In absence of gravity, the objects tend to levitate or float in the air. Gravitational force is conservative in nature, hence the force responsible for the falling of objects on the surface of the earth is known as a conservative force.
6. Spring Action
To stretch a spring, an external mechanical force is applied across its both ends. The energy contained by the stretched spring does not dissipate, but it is contained within the spring. After the mechanical force is removed, the spring regains its original shape, thereby conserving or preserving the energy. Also, the work done by stretching the spring is completely reversible in nature. Hence, the spring action is yet another example of a conservative force.