Dissipative force is a force that is capable of translating mechanical energy into thermal energy. The existence of dissipative force leads to a significant loss of energy. Therefore, the presence of dissipative force in a system leads to the generation of heat. A dissipative force must always do the negative work. Dissipative forces are also known as non-conservative forces. Examples of dissipative forces include the force of friction, resistant forces, drag, etc.
1. Tyres against Road
When a vehicle moves at a high velocity, the tires experience a huge amount of frictional force from the ground. The force of friction exerted by the ground in the direction opposite to the motion of the vehicle tends to oppose the motion. This opposition consumes a part of the energy produced by the motion of the vehicle and releases it in the form of heat. This is the reason why a number of racing vehicles catch fire while moving at a considerably high velocity. The same reason explains why the tires of a vehicle feel hot to touch after a journey.
2. Air Resistance
Air resistance is yet another example of dissipative force. Air resistance or drag is the force applied by the air in opposition to the moving object. The main objective of air resistance is to slow down the speed of the moving object. This requires the consumption of energy and its translation or dissipation into some other form. Due to the negative work being done by the air resistance hampers the movement of the object and releases a significant amount of heat energy.
3. Rubbing Stones Together
Rubbing the stones together was indeed the main reason that led to the discovery of heat energy and fire. While rubbing two stones together a force of friction comes into play. This force of friction opposes the motion of the stones and contributes to negative work. The negative work then dissipates energy in the form of heat. Hence, rubbing two stones together is a prominent example of dissipative force.
When a person forcefully drags his body against a plane surface to slide over it, heat is felt by the person at the point of contact. The force of friction existing between the body and the surface is a response force existing in nature applied by the ground to oppose the motion of the moving object. Since the work done by the force of friction is in the opposite direction, there exists a negative work. Therefore, dissipative force is said to be existing.
To light a matchstick, the tip of the stick is made to slide against the surface of the box. The sliding action of the matchstick also develops a force of friction. The motion of the matchstick is opposed by frictional force, which leads to the conversion of mechanical energy to heat energy. Hence, the action of a matchstick is yet another notable example of dissipative force.
6. Cutting a piece of wood
When a piece of wood is cut with the help of a saw blade, a huge amount of kinetic energy gets converted into heat energy. The saw blade is rubbed against the wood, which develops a significant amount of frictional force. This is the main reason why the pieces of wood and the blade feel warm after the task of cutting is completed.
7. Rubbing Hands
During the days of cold, we often rub our hands together to provide ourselves with heat and warmth. The science behind this process of heat generation includes the concept of dissipative or non-conservative forces. While rubbing hands a portion of mechanical energy gets converted into heat energy. This heat energy is accountable to provide us with the necessary warmth.
8. Sliding Rope between Hands
When a rope is made to slide between the tight grip of a person’s hands, he tends to develop burns and injuries. This is because of the interaction of the rope and the hands. Due to this agitated interaction, the force of friction comes into action. The opposition provided by the friction to the motion of the rope is utilized to generate heat energy, which is responsible for the burn injury caused to the person holding it.
A damper or a shock absorber is a mechanical part installed in most automobiles and various other machinery to protect them from sudden shocks. It reduces the chances of wear and tear of the structure as well as the mechanical failure of the device. For damping purposes, either air or fluid can be used. In a shock-absorbing mechanism, the shock is absorbed by the spring, whereas the damper helps to regulate the oscillations produced due to bouncing.