Energy is a word used in the most varied contexts, however, in the field of Physics, it designates the ability to perform work. Energy is expressed in many forms – kinetic, potential, chemical, among others – but essentially it is a physical quantityabstract, related to the movement is that nohe canto becreated or destroyed, but only transformed, through the application of a force.
Lookalso:fundamental forces of nature
Energy in Physics
THE energy it's a very complex concept and, although we talk about it all the time, we don't formally understand it, since the definition of energy involves another physical concept: work. Theoretically and simply, work is every action that is done against a strength, such as gravitational force.
The knowledge about energy is very vast and encompasses several areas of knowledge. This interdisciplinarity can be seen when we analyze the simple action of acting against gravity.
When we squat down and lift a box off the ground, we are transforming energy. This energy, which was transferred to the box in the form of gravitational potential energy, was exerted by an external force, generated from the contraction of a large number of muscle fibers. This contraction occurs when electrical current passes, which originates in specialized cells. These cells, in turn, can only produce current when they obtain energy from the chemical bonds present in food, which, when broken, release calories.
Given the complexity of the energy, we will limit ourselves to what is energy for the Physics: Energy is a greatnessphysicsclimb, whose unit of measure, according to the SI, and the joule. Energy is defined from work. When we do work on a body, that body is exchanging energy with us. O work is, therefore, the transformation or transfer of the energy that occurs to a body that is subjected to the application of a strengthexternal.
O work of a constant modulus force can be calculated as an inner product of force and distance. It is, therefore, the projection of force on the distance, that is, at work, only the distance covered in the direction of strength. See below the formula used to calculate the work:
τ – work (J – joule)
F – force (N – newton)
d – distance (m – meter)
θ – angle between force and distance
When work is performed on a body, that body undergoes increases or decreases in the amount of energy contained in it, and this manifests as variations in kinetic energy or potential. Remember that, as said, the work consists of a forminiftransferenergy, so this energy was not created, but transformed.
See too:Work: concept and ways to determine it
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What are the types of energy?
Since there are several forces in nature, there are also many forms of energy, but all are directly related to movement. Check out some examples of energy forms:
Kinetic energy: is the energy associated with movement, everything that moves and has mass has kinetic energy. This energy is directly proportional to the square of the velocity where bodies move.
Potential energy: is one that depends on the position of the body. There are many forms of potential energy, such as gravitational potential energy, the electrical potential energy, a elastic potential energy, among others.
mechanical energy: is the sum of energykinetics with energiespotentials of any physical system. US systemsphysicistsconservatives where there is no friction, mechanical energy is conserved.
Thermal energy: is that contained in bodies that are above the temperature of the absolute zero. When thermal energy is transferred between bodies, it is called heat.
Chemical energy: is the form of energy found in chemical bonds and it can be obtained from the burning of fuels, such as gasoline, alcohol, etc. Fundamentally, it is a energy of nature electric, since chemical bonds result from electrical interactions.
Electricity: electrical potential energy, known simply as electrical energy, is that which is obtained from the interaction between electrical charges, separated at a distance from each other.
Nuclear energy: is the energy that is obtained from the fission From atomic nuclei. This energy results from the interaction between protons and neutrons, who are attracted to a kind of fundamental force of nature known as strong nuclear force. Learn more about the subject by visiting our article: Nuclear physics.
Lookalso: Seven “Gold” Tips for a More Effective Physics Study
energy formulas
There are formulas that are used to calculate each of the different forms of energy. Let's check what they are and what each of their variables means:
→ Kinetic energy formula
The formula of energykinetics is such that this energy is equivalent to the product of the mass and the square of velocity divided by 2, as shown below:
m – mass (kg)
v – speed (m/s)
→ Gravitational Potential Energy Formula
The formula of energypotentialgravitational establishes that this form of potential energy is equal to the product of three magnitudes: mass, acceleration of gravity and height:
→ Elastic potential energy formula
The elastic potential energy formula is equal to the product of the constantelastic and the square of the spring deformation divided by 2. Watch:
k – elastic constant (N/m)
x – spring deformation (m)
→ Electric potential energy formula
The formula of energypotentialelectric is equal to the product of three quantities (the modulus of the two electrical charges, Q1 and Q2, and a proportionality constant, k0) divided by the distance between the charges:
k0 – electrostatic vacuum constant (Nm²/C²)
Q1 and Q2 – modules of electrical loads
d – distance (m)
By Rafael Hellerbrock
Physics teacher
