What Is Stored Energy For Grade 4?
Stored energy is energy that has been captured and held in an object or system. For example, a battery stores chemical energy, food stores chemical energy, and a water reservoir at a height stores gravitational potential energy.
Stored energy is an important concept in science because many processes and technologies rely on energy storage. Stored energy provides a supply of energy that can be used later, even if the original energy source is no longer available. This allows useful work to be done at a different time or place from where the energy originated.
Understanding stored energy helps explain how many everyday items and systems work, from the elastic energy in a stretched rubber band to the chemical energy stored in the gasoline that powers cars. Learning about energy storage also allows us to design better technologies that make efficient use of stored energy.
Forms of stored energy
There are three main forms of stored energy that are important for Grade 4 students to understand: chemical, potential, and kinetic.
Chemical energy is energy stored in the bonds between atoms and molecules. Batteries and food are two common examples of stored chemical energy. Batteries store chemical energy and release it in the form of electricity. Food contains chemical energy in the bonds between atoms, which is released when our bodies digest food.
Potential energy is stored energy due to an object’s position or shape. Water held behind a dam has potential energy because of its position high above the water below. Springs and stretched rubber bands have potential energy because they are distorted from their natural shape.
Kinetic energy is the energy of motion. Flywheels store kinetic energy in their spinning motion, which can be tapped to do work. Bows and arrows also contain stored kinetic energy due to the position of the bent bow.
Batteries store chemical energy
Batteries store energy through chemical reactions. Inside a battery, there are two different metals (like zinc and copper) that act as electrodes. These electrodes are placed in an electrolyte solution. When the battery is connected in a circuit, chemical reactions occur between the electrodes and electrolyte. These chemical reactions produce electrons, which create an electric current that can power devices. The chemicals in the battery provide the energy to move the electrons.
Some common examples of battery-powered devices are flashlights, remote controls, toys, and portable electronics like cell phones and mp3 players. Batteries allow these devices to be portable and cordless. The batteries store chemical energy from the reactions between their electrode metals and electrolytes. This stored energy is then converted to electricity that powers the devices. Alkaline batteries like AA and AAA batteries are commonly used to power small household devices. Larger batteries like D batteries or 9-volt batteries can provide more energy for more power-hungry electronics. Rechargeable batteries like lithium-ion batteries can be reused many times after being recharged.
Food Stores Chemical Energy
Food provides chemical energy that our bodies convert into usable energy to fuel our daily activities. When we eat, our digestive system breaks down the carbohydrates, proteins, and fats in food into simple sugars like glucose. Glucose enters the bloodstream and travels to cells throughout the body to provide energy. Any extra glucose gets stored for later use.
Foods like bread, cereal, pasta, rice, fruits, and starchy vegetables contain lots of carbohydrates that the body easily breaks down into glucose. Meat, fish, eggs, nuts, seeds, and legumes are high in protein, which gets converted into glucose too. Oils, butter, nuts, and other fatty foods also provide chemical energy in the form of fat calories. High calorie foods like candy bars, chips, cookies, and ice cream give big boosts of quick energy from simple sugars or fat.
The more active we are, the more chemical energy from food our bodies require. Athletes and growing children need plenty of high-energy foods to fuel their activities and growth.
Water at a height stores gravitational potential energy
When water is at a high elevation, such as in a reservoir behind a dam, it has the ability to do work. This is because the water has gravitational potential energy. Gravitational potential energy is energy that is stored due to the position or height of an object. The higher the elevation of the water, the more gravitational potential energy it possesses.
Dams are able to harness the gravitational potential energy of water by controlling its flow. When water in a high-elevation reservoir flows down through the dam, it turns turbines to generate hydroelectric power. The motion of the water as it flows downward gets converted to electricity. Dams provide a valuable way to capture the gravitational potential energy of water and convert it into a usable form of energy.
Springs and rubber bands store elastic potential energy
Springs and rubber bands are great examples of storing elastic potential energy. When you stretch or compress a spring or rubber band, you are doing work by applying a force over a distance. This work gets stored in the spring or rubber band as elastic potential energy.
The molecules in the spring or rubber band get pushed closer together when stretched. They want to return back to their resting position, so the stretched spring or rubber band can do work. Springs and rubber bands release their stored elastic potential energy and convert it to kinetic energy when they are allowed to snap back to their original shape.
Some everyday examples of springs and rubber bands storing elastic potential energy include:
- Pulling back on a slingshot stores energy in the rubber bands
- Winding up a jack-in-the-box stores energy in the spring
- Squeezing a stress ball stores energy in the elastic rubber
- Bending the prongs of a clicker toy stores energy in the steel
So in summary, springs and rubber bands are able to store energy when stretched or compressed. This elastic potential energy gets released when they snap back to their original shape.
Flywheels store rotational kinetic energy
Flywheels are devices that store energy in the form of rotational motion. They consist of a spinning wheel or disk with a heavy rim that keeps the wheel rotating smoothly. As the flywheel spins, it stores rotational kinetic energy. This stored energy in the spinning flywheel can be utilized later to perform work.
The heavier the rim of the flywheel, the more energy it can store while spinning. When an external force causes the flywheel to spin faster, energy is added to the system. This added energy gets stored as rotational kinetic energy in the increased spinning motion of the flywheel. The flywheel continues spinning until friction and air resistance slow it down.
A great example of a flywheel is a pottery wheel. The spinning disk allows potters to shape clay vessels with ease. The momentum of the spinning wheel keeps the motion going smoothly as the potter molds the clay. This demonstrates how the rotational kinetic energy stored in the flywheel is utilized to make shaping clay easier.
Bow and arrows store elastic potential energy
One example of stored energy that Grade 4 students may be familiar with is a bow and arrow. When you pull back on the bowstring, you are using force to bend the bow. This bending action stores elastic potential energy in the bow. The farther back you pull the bowstring, the more potential energy gets stored.
When you release the bowstring, the stored elastic potential energy gets converted into kinetic energy as the arrow speeds forward. The arrow flies off with kinetic energy that came from the stored potential energy in the bent bow. So a bow and arrow is an everyday object that relies on the conversion between stored elastic potential energy and kinetic energy.
Everyday Examples of Stored Energy
We use objects that store energy every day!
Your backpack stores energy when you pack heavy books inside. The straps store elastic potential energy when you wear it on your back. Your skateboard stores elastic potential energy in the springs underneath when you stand on it. Even food stores chemical energy that your body uses for fuel.
What are some other examples of everyday objects that use stored energy? Your bicycles store energy in the pedals and wheels. The lights in your home use electrical energy stored in batteries. And your bodies store chemical energy from food that lets you play and be active!
Importance of stored energy
Stored energy is extremely useful in our everyday lives. It allows us to capture energy when it is plentiful, save it, and then use it whenever we need it. Some key reasons stored energy is so important are:
Batteries allow us to store chemical energy from electricity and use it to power portable devices like phones, flashlights, and more. Without batteries, we wouldn’t be able to use our devices away from a power outlet.
Food stores chemical energy from the sun that plants absorb. We eat plants to get energy to move, grow, and thrive. Food gives us an internal source of stored energy.
Dams store the potential energy of water held at a height. This energy can then be released to generate electricity on demand, not just when the water is flowing.
Springs and rubber bands allow us to store mechanical energy and release it to power toys, gadgets, and more. Their elastic potential energy can provide bursts of power.
Overall, stored energy allows us to collect energy from various sources, stockpile it, and harness it when we need it. Without the ability to store energy, we would be very limited in what we could accomplish. Key takeaway: stored energy is essential for portability and on-demand power.
