# Which Of The Following Shows An Example Of Elastic Energy?

Elastic energy is the potential energy stored in an elastic object when work is done to deform it from its natural shape or dimension. It is stored in the object’s stretched chemical bonds, which act like stiff springs. When the external forces are removed, these chemical bonds return to their relaxed state, releasing the elastic energy and allowing the object to regain its original shape. Examples of elastic energy can be seen around us everyday. This form of potential energy plays an important role in many natural processes and engineered devices.

Some common examples of elastic energy include springs, rubber bands, trampolines, bows, catapults, tendons, ligaments, piezoelectrics, and flywheels. These objects are able to store energy when stretched, compressed, or twisted from their relaxed state. Their elastic properties allow them to return to their original shape when released, converting the stored elastic potential energy into kinetic energy. Harnessing the storage and release of elastic energy has many useful applications, from powering toys to launching projectiles to storing energy in power plants. Overall, elastic energy is a versatile form of potential energy that exists in any elastic material. This introduction will provide an overview of the different examples and applications of elastic energy.

## Springs

Springs are a classic example of elastic energy in action. A spring can be compressed or stretched from its resting position to store mechanical energy. This stored energy of position is referred to as potential energy. When released, the spring converts the potential energy into kinetic energy as it returns to its original shape.

The tendency of a spring to return to its original length is described mathematically by Hooke’s law. Hooke’s law states that the force (F) needed to extend or compress a spring by some distance (x) is proportional to that distance. The relationship is given by:

F = -kx

Where k is the spring constant that depends on the spring’s material and construction. According to Hooke’s law, springs store more potential energy when stretched or compressed further from their relaxed length.

Examples of springs storing elastic energy include:

• Coiled metal springs in mattresses or vehicle suspensions.
• Spring-loaded pogo sticks that store energy in the compression of the spring.
• Slinky toys that can bounce up and down due to the elastic properties of the coiled metal spring.
• Mousetrap games that use the potential energy in a wound up spring to propel parts into motion.

In all these examples, the elastic properties of metal coil springs allow them to store mechanical energy when deformed from their natural lengths. This energy can then be recovered to power kinetic motion.

## Rubber Bands

Rubber bands are a common example of an object that exhibits elastic potential energy. Rubber bands are made of elastic material, usually rubber or latex. When a rubber band is stretched, the polymer chains in the rubber are also stretched. The stretching of the polymer chains stores elastic potential energy in the rubber band.

The more a rubber band is stretched, the more elastic potential energy is stored. This energy gets converted into kinetic energy if the rubber band is released. The elastic properties of rubber bands allow them to return to their original shape after being stretched and released. This repetitive stretching and releasing can demonstrate the elastic potential energy.

Rubber bands have many uses that take advantage of their elastic properties. They are commonly used to hold objects together, like closing bags or binding several items. Their stretchiness allows them to create tension and grip items securely. Rubber bands are also used in science experiments and physics demonstrations of energy. Their ability to store and release energy makes them useful for showing elastic potential in action.

## Trampolines

Trampolines are a great example of elastic potential energy in action. The mat of the trampoline is made of strong fabric, often nylon or polypropylene, with steel springs connecting it to the frame. When a person jumps on the trampoline, their kinetic energy causes the mat to stretch downward, storing elastic potential energy in the springs. As the springs rebound, this elastic potential energy is converted back to kinetic energy, launching the jumper upwards.

The longer and more stretchable the springs are, the more the trampoline mat can stretch and store this elastic energy. Good quality trampolines are engineered to optimize the elastic potential energy storage and return. The person jumping supplies initial kinetic energy, which gets turned into potential energy in the springs during the landing. This potential energy then gets released again as kinetic energy to power the upward launch.

Safety concerns with trampolines include preventing falls off the sides onto hard surfaces and limiting multiple jumpers at once. Enclosure nets around trampolines can help prevent falls. Also, the mat and springs can wear out over time. Proper maintenance and weight limits help mitigate safety risks of worn out components. When used properly, the elastic properties of trampoline springs provide an entertaining way to experience the cyclic transfer of kinetic and potential energy.

## Bows and Catapults

Bows and catapults are weapons that store elastic potential energy by bending flexible materials like wood or composite fibers. As the bow is drawn back or the catapult arm is bent, the material bends and elastic energy is stored. When released, the bending material springs back to its original shape, converting the stored elastic energy into kinetic energy that propels the arrow or projectile forward.

Archery bows store energy when the archer draws back the bowstring, bending the limbs. Crossbows use a mechanism to bend the bow limbs and hold them until fired. Catapults like the onager and trebuchet use the tension of twisted rope or a bent beam to store energy. In both cases, the further the flexible element is bent, the more energy is stored for propulsion. This makes them an effective means of hunting prey or attacking fortifications.

Bows and catapults were among the first mechanical weapons that allowed ancient human civilizations to more effectively hunt animals for food and attack rival tribes. Lightweight bows revolutionized warfare tactics with their accuracy and rapid firing rate compared to earlier weapons like slings or spears. The Romans were among the first to develop torsion catapults that could hurl heavy projectiles to batter down fortified walls. Later medieval designs like the trebuchet further improved range and destructive impact using counterweights. Overall, these weapons demonstrated early applications of elastic energy storage in devices that increased human strength and changed the course of history.

## Tendons and Ligaments

Tendons and ligaments are examples of connective tissues in the body that exhibit elastic properties. They are able to store energy when stretched or deformed and then release that energy when they return to their original shape.

When running or jumping, the tendons in the legs and feet stretch and deform as force is applied. As they stretch, they store elastic potential energy. When the foot leaves the ground, the tendons recoil to their original shape like an elastic band, releasing the stored energy and providing additional power and momentum for the jump or stride.

Ligaments work in a similar way to stabilize joints and provide elastic recoil. For example, ligaments around the knee store energy as they are stretched when the knee bends. As the knee straightens, the ligaments release this energy and help drive the motion.

The elasticity of tendons and ligaments makes them act like springs or rubber bands. This allows them to efficiently store and release energy with minimal energy loss for optimum biomechanical function. Their elastic properties are essential for effective running, jumping, and stabilization during exercise and athletic activities.

## Molecular Bonds

At the molecular level, elastic energy arises from the stretching and vibrating of chemical bonds that hold molecules together. Some types of bonds, like covalent bonds between carbon atoms, can stretch and bend without breaking. This gives certain large molecules and polymers elastic properties.

A classic example is vulcanized rubber, where long chains of carbon atoms are cross-linked together. When you stretch rubber, the carbon-carbon bonds lengthen and rotate, then snap back to their resting state when released. Another type of elastic polymer is cellulose, found in plant cell walls. The hydrogen bonds between cellulose fibers can bend and straighten repeatedly as the plant sways in the wind.

DNA and proteins also contain many flexible covalent bonds in their backbone structures. This allows DNA to unwind and re-form during replication and transcription, and lets protein molecules fold into complex shapes. On a larger scale, the web of sacrificial hydrogen bonds between water molecules gives water surface tension and capillary action. Even steel exhibits elasticity on the nanoscale from the stretching and re-forming of metallic bonds.

## Flywheels

Flywheels are devices that store energy in the form of momentum by spinning a mass around an axle. The momentum that flywheels store can be immense, allowing them to smooth out power delivery in applications like vehicles and generators.

A flywheel resists changes in rotational speed, which allows it to act like a reservoir of energy. Energy can be added to the flywheel by spinning it faster, and energy can be extracted by allowing it to spin slower. The more massive the flywheel, the more energy it can store.

Flywheels are often used in combustion engines. As each piston fires, it gives an uneven impulse of force. But because the crankshaft acts as a flywheel, it resists changes in rotation and smoothes out the power delivery to the wheels. This allows the wheels to spin at a steady pace even as each piston delivers pulsating force.

Similarly, flywheels are used in power generators. The input torque from the turbine or engine may fluctuate, but the flywheel ensures steady rotation as power is delivered to the generator. This results in clean and consistent AC frequency and voltage output.

Flywheels can also provide backup power in case of a power outage. The flywheel’s momentum can drive a generator to produce electricity until other power sources come online. In this way, flywheels provide energy storage and bridge gaps in power availability.

## Piezoelectrics

Piezoelectric materials demonstrate elastic energy by converting mechanical energy into electricity. When these materials are subjected to mechanical stress or vibration, they generate an electrical charge proportional to the applied stress. This phenomenon is called the piezoelectric effect.

Some common piezoelectric materials include quartz, certain ceramics, bone, DNA, and various proteins. In manufactured piezoelectrics, the materials’ crystals are oriented to optimize the piezoelectric effect.

The piezoelectric effect allows these materials to be used as sensors and switches. For example, piezoelectric sensors can detect changes in pressure, acceleration, temperature, strain or force by converting these mechanical stimuli into an electrical signal. Piezoelectric materials can also function as actuators, as applying an electric field to them induces mechanical deformation and vibration.

Piezoelectrics have applications in a wide range of fields. They are used in frequency standards, vibration sensors, ignition systems, ultrasonic transducers, microphones, headphones and more. Overall, piezoelectrics demonstrate elastic energy through their unique ability to interconvert mechanical and electrical forms of energy.

## Conclusion

In this article we explored several real-world examples of elastic energy in action. Springs, rubber bands, trampolines, bows, catapults, tendons, ligaments, and piezoelectric materials all demonstrate the ability to store energy when deformed and release it back when the force is removed. Even at the molecular level, energetic chemical bonds behave elastically. The common thread is that elastic materials have the capability and tendency to return to their original shape after being bent, compressed, or stretched.

The concept of elasticity has many important engineering and scientific applications. Everything from suspension systems on vehicles to synthetic rubber requires an understanding of how material elasticity works. Knowing how much energy can be stored and released by a given material helps engineers design safer, more efficient systems and mechanisms. By continuing to study elastic materials, scientists uncover new properties that lead to advanced applications like flexible circuits and energy harvesting devices.

Overall, elastic energy is an essential phenomenon that contributes to many facets of everyday life. The ability to temporarily store mechanical energy and release it on demand gives elastic materials unique and valuable functionality across industries. Without harnessing the principles of elasticity, we would lack many of the useful tools, products, and technologies that we rely on today.