Table of Contents
The law of energy conservation is one of the important laws in physics. To understand the law of conservation of energy invented by AI as well as making relevant statements and formulas, please refer to the following article.
What is energy?
The main energy is characterized by the ability of an object to be born. The index of this energy is related to the movement of particles and magnetic fields. The energy and mass of the object are related to each other based on relativity.
In physics, energy is considered a preserving quantity. The law of conservation of energy tells us that the energy is not naturally born nor naturally.
Earth's organisms need energy to live, such as people with energy through food. The current civilization requires energy to operate, it takes energy from sources such as stone stone, nuclear or regeneration, …
Statement of energy conservation law
In chemistry and physics, this law is understood: “The total energy of a isolated system is always constant and means it will be preserved over time.”
Since then we have a speech about the law of preserving specific energy as follows:
“The energy will not be naturally born or lost, but they will move from one form to another or from one object to another.”
These explanations may be similar to the explanation of the object's function why increases or decreases. In addition, it also explains why things cool down or heat up. All are based on the metabolism of energy in the phenomenon of heat, muscle or electricity in nature. In addition, they also affirm the conversion of objects based on the law of conservation.
For example:
Drop a marble into the cup. At this time, the energy of the ball is attractive. When the marble falls into the cup, it moves around the cup for a while and this time will be kinetic. At the same time, when it falls, it also creates a sound that is negative. In addition, when the ball falls, there will be frictional movement with the cup surface, producing heat.
Thus, when dropping the marble into the cup not only has an initial form of energy, the marble has transformed into at least three new types of energy, the kinetic energy, sound, and heat.
The basis forms the principle of energy conservation
To know what is the law of conservation and energy metabolism? We will rely on the following establishments:
1. Change potential potential into kinetic energy and vice versa. Mechanical loss
People have seen the transformation from the potential into kinetic energy and vice versa before knowing the law of conservation. In natural phenomena, we will see the clear change between potential and kinetic energy. Mechanical energy will be converted into energy thanks to the loss parts in the mechanical energy and can be said that the mechanical energy is always decreasing.
2. Change mechanical energy into electricity and vice versa. Mechanical loss
In the case of a loss based on the law energy, the function occurs when the function is transformed into electricity and vice versa. In most current electric motors, we see that the electricity will be converted into mechanical energy. As for generators, the opposite, most functions will convert into electricity.
If the energy is increased compared to the original, we can see that it is another energy that has been transformed into.
Who discovered the law of conservation of energy?
The law of energy conservation is a process of research by many scientists and émilie Du Châtelet is the one who has proposed and tested first.
After the mechanics was born in 1826, James Prescott Joule proved the transformation of energy from function to heat in 1854. Until the 1981s, Julius Robert Mayer – German physicist made speeches on energy conservation.
When many researchers found and proved correctly, physics only recognized Julius Robert Mayer as the author of the law of conservation of energy.
The formula for preserving the energy in the motor oscillation
In essence, the energy in the motor oscillation is called mechanical energy, they will be equal to the total kinetic energy and potential according to a constant mechanical enclosure system. So:
What is kinetic energy?
The kinetic energy is the form of energy generated from its motion. When an object is dynamic, the object can act on another object and will be generated.
Formula for calculating the kinetic energy of free falling objects:
In there:
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WD: Is the kinetic energy of the object (j)
-
M: The mass of the object (kg)
-
V: is the velocity of the object (m/s)
What is the power?
The energy of a quantity in Physics, shows the ability of the object and it exists in the form of energy.
The formula for the potential of a free falling object:
|
Wt = mgh |
In there:
-
WT: The energy of the object (j)
-
M: is the weight of the object (kg)
-
H: is the height of the object when falling freely (m)
Mechanical preservation expression
The function of the main object is a preserving quantity when moving in gravity is only subject to gravity.
|
W = WĐ + WT = const (constant) |
In there:
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WD1: is the kinetic energy of the object at the position of velocity v1
-
WD2: is the kinetic energy of the object at the position of velocity V2
-
WT1: is the energy of the object at the height of H1
-
WT2: is the energy of the object at the height of H2
Based on the expression above, we see that:
An object when falling freely, the kinetic energy will be 0 if the power time is maximum. The function is 0 when the kinetic energy reaches the maximum. Increasing energy, the kinetic energy will decrease, but the sum of the potential and kinetic energy is a constant quantity.
See also: What is the formula for the velocity? How to apply (10th grade physical answer)
The formulas related to the law of conservation of total energy
After knowing whose law preserves the law? As well as the concept of this law, below will be some related formulas and exercises for students to practice:
The formula for calculation
|
A = fscosα |
In there:
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A: The force of force f (the unit is j)
-
F: The force acting on the object (the unit is n)
-
S: The distance of the object moves (the unit is m)
-
The unit of the public is Jun (denoted J).
1J = 1n.1m = 1nm
1 kJ = 1000 J
Jun's multiple is Kilojun (KJ)
Average capacity
|
P = a/t |
In there:
-
P: Capacity (the unit is J/S or W)
-
A: Performance (the unit is NM or J)
-
T: The execution time (the unit is s)
1KW = 1000W; 1mw = 1,000,000w
Instantaneous capacity
|
P = fvcosα |
Contact expressions
Dynamic:
Contact between kinetic and public:
|
ΔWĐ = WĐ2 – WĐ1 = AP (The external force is f) |
Gravity function:
|
Wt = mgz |
Contact the gravity and public energy:
|
ΔWT = WT1 – WT2 = AP |
The work of gravity (falling):
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AP = MGH (When the object goes up, add the “-“) |
Elastic energy
|
Wt = kx^2 |
Contact the elastic and public energy:
|
-ΔWT = WT1– WT2 = AFDH |
Function:
|
W = WT+ WĐ |
The law of conservation of energy:
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WĐ1 + WT1 = WT2 + WD2 (The power is only preserved when there is no external force control) |
The kinetic height is equal to n times:
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H = Ho/(n + 1) (If the ability is equal to m kinetic energy, replace n = 1/m and only use when doing test or test results) |
Efficiency:
|
H = ACI/ATP |
In there
- ACI: useful
- ATP: Complete work
|
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Application of the law of conservation of energy
Newton's law of conservation of energy is widely used in many areas of life and science. Here are some typical applications:
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Application in machinery and engine: The fuel is converted into heat and then into mechanical energy to operate equipment such as cars, motorcycles, generators.
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Application in renewable energy: energy from the sun, wind, water is converted into electricity used in daily life and production.
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Application in chemistry and biology: Energy in chemical reactions and metabolic processes are metabolized to provide energy for the living body.
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Application in construction and technology: Calculation and control of energy help ensure safety and efficiency for works such as bridges, dams, high -rise buildings.
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Application in electronic devices: Electrical circuit design and electrical consumption device to optimize metabolic performance and reduce energy waste.
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Application in education and research: Used to explain physical phenomena, as a basis for practical problems and experiments.
Some exercises to illustrate the law of conservation of energy
After grasping the theory of energy conservation, here are some related exercises for them to practice together:
Some practice exercises on self -training conservation
I: Test section
Lesson 1: In natural phenomena, there is often a change between:
A. Electricity and potential
B. potential and kinetic energy
C. optical and kinetic energy
D. Chemistry and electricity
Lesson 2: In the process of transforming potential potential into kinetic energy and vice versa in natural phenomena. The function always decreases, the depleted muscle part has transformed into:
A. Thermal energy
B. Power
C. Quang Nang
D. Nuclear energy
Lesson 3: In the electric motor, most of the electricity transforms into:
A. Electricity
B. Power
C. Quang Nang
D. Mechanical energy
Lesson 4: Choose the correct statement.
A. In electric motors, most of the electricity converts into heat.
B. In generators, most of the function converts into function.
C. The useful energy of the last obtained is always greater than the original energy supplied to the machine.
D. The loss of energy is transformed into another form of energy.
Lesson 5: Which of the following statements is true when talking about the law of conservation of energy.
A. Energy can be generated or disappeared by themselves and moves from one form to another or transmits from one object
B. The energy does not produce itself and self -loss but can be transmitted from one object to another
C. Energy does not produce itself or disappears itself, but only moves from one form to another or transmits from one object
D. The energy does not produce itself or self -loss but only moves from one form to another
Lesson 6: In the generator, the obtained electricity always has a value less than the function for the machine. Why?
A. Because an electric unit is larger than a mechanical unit
B. Because part of the function has transformed into a format other than electricity
C. Because part of the function has disappeared itself
D. Because of higher power quality than mechanical quality
Lesson 7: In the process of transforming from kinetic energy and vice versa, what always happens to the function?
A. Always preserved
B. Always increase
C. Always lost
D. Sometimes it increases, sometimes decreases
Lesson 8: Solar battery efficiency is 10%. This means: If the battery receives:
A. Electricity is 100J, it will create optical energy of 10J
B. Solar energy is 100J, it will generate electricity of 10J
C. Electricity is 10J, it will create optical energy of 100J
D. Solar energy is 10J, it will generate electricity of 100J
Lesson 9: Speaking of electric motor efficiency is 97%. This means that 97% of the used electricity has been converted into:
A. Functional
B. Thermal energy
C. Function and heat energy
D. other energy and energy
Lesson 10: Which of the following phenomena does not comply with the law of energy conservation?
A. The stove cools down when turning off the fire
B. The car stops when turning off the engine
C. The table is cooled when turning off the electricity
D. no phenomenon
II: Essay
Thus, through this article, we have better understand what the law of conservation of energy is, whose law conservation laws and formulas related to the law of energy conservation. Hopefully this information will help you master as well as review the knowledge that is both fully and best. Please follow the basic knowledge category to be able to find out more interesting information about the subjects!
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