Give Two Examples of Mechanical Energy
Mechanical energy is not just something you learn about in a high school physics classroom. It's all around us. Mechanical energy can be found in a truck moving down a highway or a basketball when it's in the air. It is present in everyday life such as in engines, cranes , and even artificial lakes. It's one of the driving forces of the world we live in.
There are two types of mechanical energy: potential energy and kinetic energy. Both of these will be discussed further to help you gain a better understanding of mechanical energy and how it's a part of your everyday life.
What Is Mechanical Energy?
Mechanical energy is the energy a body has due to its movement or position. A good example would be the energy that is released while falling from a certain position. Mechanical energy is one of the basics studied in mechanical engineering, as it is literally the driving force of the world around us, be it natural or man-made. Mechanical energy is expressed in joules.
What Are the Different Types of Mechanical Energy?
There are two types of mechanical energy: potential energy and kinetic energy . Combined, the sum of the two is called the total mechanical energy. Mechanical energy is limitless in nature.
Potential Energy
Potential energy is the force that a body could potentially develop if it were put into motion. Potential energy is not the energy of movement. Instead, it is the energy stored in a body due to its physical properties, such as the mass or position of the object.
Gravitational potential energy is the best example of potential energy. Imagine throwing a basketball high up in the air. The trajectory of the ball is simple: it goes up, it reaches its highest point, stays there for a moment, and then starts falling back down. At its highest point, the ball has maximum potential energy. At a point in time where it does not move (however brief that moment may be), it has no kinetic energy. When an object is exposed to gravitational force, its potential energy increases.
There are different forms of potential energy , such as elastic potential energy, gravitational potential energy, electric (electromagnetic) potential energy, and nuclear potential energy.
The way to calculate the potential energy and the maximum kinetic energy of the object is the mgh formula: PE =mgh , where:
- PE: potential energy
- m: mass of the object
- g: gravity (9.81 m/s2) taken as a net force (excluding any other energy that may be influencing a body) and
- h: the height of the object
The mechanical energy of an object is therefore proportional to the mass, object height, or vertical position of the object.
Kinetic Energy
Unlike potential energy, kinetic energy is the mechanical energy of movement or energy of motion, rather than position. The faster the movement, the higher the kinetic energy . The top speed that a body could develop while moving is the highest kinetic energy of that body.
Let's go back to our basketball example: the ball goes up, reaches its highest point, and falls back down. In the first phase, as the ball goes up, it loses its speed due to gravity, so its kinetic energy reduces. As it falls back down, it gains momentum and as its speed increases, its kinetic energy increases. The very moment it hits the ground, its kinetic energy is at its maximum before it turns to zero (assuming it does not bounce back).
Total Mechanical Energy
Total mechanical energy refers to the sum of the potential energy and the kinetic energy a body may have. In a single event, the sum of the two types of mechanical energy is always the same. Sure, the potential and kinetic energy change rapidly as the ball goes up and down, but their sum is always the same.
While the ball is going up, it loses its kinetic energy . However, energy cannot truly be lost and it simply gets converted to potential energy — or heat, which is really a disorderly mix of kinetic and potential energy . As the ball falls back down, its kinetic energy increases as the ball gains momentum. This kinetic energy cannot appear out of thin air. Instead, it is the potential energy that the ball acquired while going up that is now being translated into kinetic energy.
What Does Mechanical Energy Do?
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If mechanical energy cannot be lost nor pulled from thin air, why does the ball not bounce up and down indefinitely? This is a very valid question since, theoretically in the absence of other forces, it really should bounce eternally . However, as it travels through the air, a part of its kinetic energy might seem like it's "lost" due to friction between the air and surface of the ball. However, the total energy of the system stays the same.
This is similar to fan blades: the blades lose some of their kinetic energy due to the friction and air resistance, but instead of slowing down, the blades keep spinning because they are powered by the motor. The kinetic energy transferred to the air can be felt as the breeze coming from the fan. This kinetic energy can be quite strong: just imagine the kinetic force needed to keep a chopper or airplane in the air.
What Are 5 Mechanical Energy Examples?
There are many examples of mechanical energy in both nature and our man-made world:
- Gravitational Potential Energy : When something is in a high position, it has high gravitational potential energy . The higher an object is, the faster the speed it would achieve when falling downward. Think of dropping a coin from your hand compared to dropping it from the top of the Empire State Building. Which coin reaches a higher speed? The power the coin gets from its position and motion is an example of mechanical energy.
- Moving Objects : Moving cars, trucks, boats, airplanes, even birds in the air all have a certain amount of kinetic energy . The heavier the object that moves and the higher its speed, the higher the kinetic energy it has. Imagine the kinetic energy of a pellet coming out of a BB gun. Now think of the kinetic energy needed to keep an entire airplane at 30,000 feet.
- Roller Coasters : These stomach-turning rides from your childhood offer amazing examples of both potential and kinetic energy . The roller coaster ride starts by going up, building up potential energy. Once you've reached the top of the rail, the carriage drops and the acceleration you experience is your own potential energy being translated into kinetic energy. Every time you go up, the potential energy builds and the kinetic energy diminishes. It's this constant fluctuation between the two types of energy that makes roller coasters so fun!
- Bowling Ball: Here's an example of kinetic energy. The potential energy of the ball depends on how fast you can make it roll towards the pins. The energy that knocks down the pins as the ball touches them is the kinetic energy of the ball. Since the total energy of the system is always the same, the ball has lost some of its kinetic energy and now moves forward at a slower rate.
- Hydro Plants : These provide an example of potential energy, as water is stored in artificially created lakes to be released for the creation of electricity — using gravitational potential energy to spark kinetic energy . The artificial lake is built as high as possible for a reason: the higher the water column, the higher the potential energy of the water. Once the water is released, the potential energy is quickly translated into kinetic energy which hits the turbines. The circular motion of the turbines generates electrical energy. In this case, the kinetic energy of the water is translated into electrical energy. The bigger the dam, the more potential energy the water can store and the higher the power output.
What Is Mechanical Energy Production?
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Mechanical energy production starts from the basic notion that total mechanical energy is equal to the sum of the potential energy and the kinetic energy. For example, when you need to produce mechanical energy to move your car, your engine converts the chemical energy stored in the gas to kinetic energy to move your engine. Also, an electric car converts electrical energy to mechanical energy . This reduces its potential energy and increases the kinetic energy.
What Is Renewable Mechanical Energy?
Renewable mechanical energy is any mechanical energy that is produced by renewable energy sources . For example, sailboats get their mechanical energy from the power of wind. Wind power is also used to produce electricity in wind turbines. The renewable energy of water is converted into mechanical energy in both rafting (to move the raft) and hydro plants, to spin the turbines and produce hydroelectric power . Renewable mechanical energy is also available in any electric car as long as the electricity stored in batteries comes from renewable sources, such as solar energy.
Potential Energy vs. Kinetic Energy
Potential energy and kinetic energy are both different types of mechanical energy. While the potential energy of an object depends on the position of the body, kinetic energy is the energy of motion for that same body.
The potential energy of the object is equal to the amount of work that needs to be done, or the amount of work that the object can do, to move the object to a certain position. A parachuter jumping out of a plane has maximum potential energy the moment they jump out of the plane. This energy is quickly converted into kinetic energy as they start falling down.
While the kinetic energy increases as they fall down, the potential energy decreases. In an imaginary scenario where they do not open the parachute, they would reach the maximum kinetic energy on impact, while the potential energy would be equal to 0. To prevent this from happening, they open the parachute. Air resistance and parachute friction allows for a gentle landing and prevents injuries.
Where Does Mechanical Energy Come From?
Mechanical energy comes from the position of a body and its speed when it is moving. The two energies can be combined as well. For example, when you're driving your car at 60mph, there is still a lot of potential energy that can be released by accelerating the gas pedal.
Where to Find Mechanical Energy?
Mechanical energy can be found everywhere around us. Any object that moves has some mechanical energy. An object that does not move also has mechanical energy — but it's of the potential energy type. Think of mountains and how much mechanical energy they store — any landslide is proof of how much energy they can release.
What Is Mechanical Energy For Kids?
Mechanical energy is the energy that moves an object. It is also the energy of a body that is falling down. When a toy falls, it has mechanical energy. The higher the toy is when it starts falling, the more mechanical energy it will have during the fall.
What Is Mechanical Energy in Science?
Mechanical energy in science is any energy found in a moving object. It's a macroscopic type of energy that remains constant in the system. The system itself should not be receiving any energy from outside of the system, as this additional energy could interfere with system performance.
On a molecular and atomic level, mechanical energy is seen in molecules that move or vibrate around their resting positions. This is otherwise known as thermal energy. The more energy there is, the hotter the body gets. This is known as microscopic mechanical energy or thermal energy.
What Is the Conservation of Mechanical Energy?
The theorem of the conservation of mechanical energy is a physics law, or a law of conservation of mechanical energy. The law states that in a closed system, the total mechanical energy always remains the same. This means that there are no forces such as air resistance or frictional forces to dissipate the mechanical energy. Such dissipating forces are also known as nonconservative forces. In a closed system, mechanical energy cannot be destroyed or created, it merely switches from potential to kinetic energy and vice versa.
How Is Mechanical Energy Not Conserved?
Mechanical energy is not conserved in systems that are not entirely closed. Such systems may be prone to external forces which may increase or decrease the mechanical energy of the system. Such force acts in a way that compromises the integrity of our experimental system. Furthermore, some dissipating mediums may prevent mechanical energy conservation.
How Much Mechanical Energy Is Lost in the Collision?
During a collision, the total mechanical energy is equal to the sum of the kinetic energies of the bodies that are colliding . For example, this may be as simple as a car hitting a stone wall or two cars hitting each other on a highway. In this type of collision, the entire kinetic energy is translated back into potential energy while the other part of it is translated into the forces that crushes the cars. The same principle can be observed on any other type of collision, be it a wrecking ball or a glass hitting the floor.
Mechanical Energy Is Part of Our Everyday Lives
It's abundantly clear that mechanical energy is everywhere around us, permeating our existence in ways both seen and unseen. It is used to move objects, create conveniences, and help us achieve what we cannot do with human power alone. From hydropower to wind power to the machines that make the machines that generate electricity, mechanical energy is not only present but it's the driving force.
Tara Energy provides the electricity needed for all your modern appliances, gadgets, and machines that turn mechanical energy into the working world we see around us. We may not always think about it, but this energy is always the doing work whether we notice it or not. Reliable power makes mechanical energy a reliable part of our lives, allowing us to do more than our ancestors even dreamed was possible.
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Give Two Examples of Mechanical Energy
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