Physics is the core of reality, and is basics of chemistry ,biology, architecture, engineering, geology and more.
Here is the list of physics
Classical Physics
It deals with motion of bodies, from projectile to astronomical objects you can commonly see it as what we experience in daily life is based on classroom mechanics.
Father of classic mechanics,
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| Portrait of Newton at 46 by Godfrey Kneller, 1689 |
The greatest scientist of all time. He introduced us with the three laws of motion and very famous law of gravitation.
Basics
Force :- force in classical physics is push or pull.
Mass :- mass is a measure of inertia, resistance of change in motion.
Acceleration:- acceleration is the rate of change in velocity
a = (v - u) / t
Momentum:- Motion of a moving body, measured as a product of its mass and velocity.
P = m v
where,
P = momentum
m = mass
v = velocity
Ex:- When a bullet is fired from a gun, the gun recoils or moves backward. This is because the total momentum of the gun and bullet before firing is zero. After firing, bullet moves forward, the gun moves in the backward direction. So that the total momentum is conserved.
Impulse:- Impulse is defined as the product of the force and the time for which it acts and is equal to the total change in momentum.
I = F × t
Where,
I = impulse
F = force
t = time
How is equal to total change in momentum?
Here is how,
I = F × t | F =ma
I = (Ma) × t | a = (v - u) / t
I = m (v-u) / t (t) | t and t cancel out
I = mv - mu
Hence impulse is equal to change in momentum.
3 laws of motion
1st law :- An object at rest times to remain at rest and an object in motion tends to remain in motion until and unless a net external force is applied to it. This law is also known as law of of inertia.
Ex :- When we feel a force that push us to side when car makes a sharp turn.
2nd law :- The rate of change of momentum is equal to the net external force applied by the body.
F = m a
Ex:- pushing a box, kicking a football.
3rd law :- To every action, there is always an equal and opposite reaction.
Explanation: Consider a body B exerts a force on body A (action) FAB then the body A exerts an equal and opposite force on body B (reaction) vec FBA
FAB = -FBA
Ex:- While walking we press the ground (action) with our feet slightly slanted in the backward direction. The ground exerts an equal and opposite force on us. The vertical component of the force of reaction balances our weight and the horizontal component enables us to move forward.
Force
F = m a
a = F / m
This formula tells us, if we apply a force to a fixed mass, how much acceleration it would get.
Knowing acceleration you can make predictions like where an object would be in a certain time in space.
So, with the simple formula I can predict where this football is and where it's going. If I know all the formula is acting on it including friction in air.
The same formula can be used to determine how much reinforcement needed to build a bridge.
Funfact
Your body doesn't have a force. It has a mass. Your weight is the force your body exerts on the ground.
Technically, you doesn't wait 60 kgs you should weight 588 N. Mass times acceleration due to gravity on earth which is 9.8 m/s² is your weight.
Universal law of gravitation
This law says, gravitational attraction between two bodies is the product of their mass divided by the square of the distance between them, times a constant called universal gravitational constant (value :- 6.67 × 10-¹¹ )
F = G M1 M2 / r²
Energy
Energy is not a vector like force or momentum. Work and energy have the same units [joules (j)]
Work is force times distance travelled.
W = F × S
W = work
F = force
S = displacement
Ex:- if you push your Box 1 m applying a force of 1 Newton then it takes 1 joule of energy to move the box.
Total energy = kinetic energy + potential energy
Kinetic energy
Energy a body gets by virtue of being in state of motion.
Ex:- (any object in motion is using kinetic energy)
A person walking a charged, a charged particle in an electric field.
Formula
KE = 1/2 mv²
Potential energy
If you are carrying your phone and excellently drop seat your phone is probably going to be damaged. But where did the energy come from to damage the phone? Phone had gravitational potential energy when you were holding it near your ear. The potential energy was then converted to kinetic energy as it fell.
Formula
PE = mgh
Energy can neither be created nor be destroyed it only changes the form.
Thermodynamics
It is the study of work, heat and energy of a system. If a car applies the break, the kinetic energy of the car becomes zero. Where did the energy go? It did not go to gravitational potential energy and also is not stored somewhere. Did it disappear? No, it was converted to thermal energy, created by friction of the car's brakes. Heat is a flow of thermal energy from one object to another. Thermal energy created by the brakes raises the kinetic energy or movement of molecules in the air, this results in a temperature increase of the surrounding air. This is ultimately where the kinetic energy of your car ends up after you come to a stop. Temperature is the average kinetic of atoms in a system. Thermal energy is the total amount of kinetic energy of atoms in a system. Another concept in thermodynamics is the idea of entropy. Entropy is a measure of disorder, but more accurately, it is a measure of the information required to describe the microstates of a system. The 2nd law of thermodynamics states that the entropy of an isolated system can never decrease.
If you put two liquids together in a bucket, and
one is very cool and the other is very hot, why can't you get it such that the cold part gets colder and the hot part gets hotter? Energy could still be conserved because the decrease in thermal energy of the cold water, could be offset by the increase in thermal energy of the hot water. The reason this does not happen is because of the 2nd law. The universe is on an inexorable path to higher and higher entropy, or more and more disorder. Practically what this law tells us is that some energy is more useful for doing work than others. Energy at lower entropy can do more work than energy at higher entropy.
For example, the energy stored in gasoline is more useful for doing work, than the thermal energy that is dissipated from the brakes of your car. An orderly energy is more useful than one that is less orderly. The heat and exhaust from the car will not spontaneously rearrange itself to become the gasoline. But gasoline can be converted to heat and exhaust. It is important to remember the words "isolated system". If you
put a glass of water in the freezer, it will decrease in entropy. But the freezer is not an isolated system because the refrigerator uses energy from electricity to cool the inside.
It increases entropy of the room by heating up the room more than cooling what's inside the refrigerator. You should also remember this fact: The one way flow of Entropy appears to be the only reason we have a forward direction of time.
Electromagnetism
Electromagnetism is the study of the interaction
between electrically charged particles. The essential concepts are embodied in Maxwell's
equations. Objects have something called a charge. We don't know what it is. It is just a property of certain types of matter such as electrons. If a large object has a negative charge, this means it has more electrons than protons.
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| Maxwell's equations |
1st equation:- if you have an electrical charge, there will be an electric field emanating from it.
2nd equation:- it is basically the same concept for magnets, except that magnets will always have as many field lines going out, as coming back in. Another way to say this is that magnets will always have 2 poles, a positive and negative pole. It can never be a monopole. You can keep breaking up a magnet, but it will always form a new magnet with 2 poles.
3rd equation :- If you move a magnet, you will create an electrical field. This means that if a charge is nearby, it will feel a force. This is how electricity is generated by moving magnets.
4th equation:- an moving charge or moving electrical fields create a magnetic field. I want you to take note of the constants μo and ε0
are the permeability and permittivity of free space, respectively. These two constants determine the speed of light because they measure the resistance of space to changing electrical and magnetic fields.
Planck's constant
It says that energy is not continuous, but is quantized. The energy absorbed or emitted
by materials can only occur in distinct quanta of energy. And the amount of energy equals the frequency of the radiation times a constant, called Planck's constant. Using this concept,
Einstein later showed that a photon is both a wave and a particle.
The energy of a single quanta of electromagnetic energy is given by E = hμ, where h is the planck's constant.
Energy = h×μ
h = planck's constant (6.6 × 10-³⁴ )
μ = frequency
Uncertainty principle
This equation says you cannot know both a particle's exact position and it's exact momentum at the same time. For a particle with mass, this means that if you know exactly where a particle
is, you don't know how fast going. And if you know exactly how fast it's going, you have no idea where the heck it is. There is an inherent uncertainly associated with quantum particles.
Schrödinger equation
Quantum systems are in superposed states. This means that their properties can only be expressed in terms of a wave function. A wave function crudely simplified is a set of probabilities. So for example, in a hydrogen atom, you can't know where to find the electron in advance. All you can know is the probability of where you might find it, if you measured it.
All quantum systems are 3 dimensional clouds or waves of probabilities. The electron is everywhere at once. It's not here or there. It is here and there. This is not a limitation of our measuring devices. It is a limitation of reality. And this is the reason quantum systems behave so mysteriously in the double slit experiment.
A quantum system can be an elementary particle like an electron, or even atoms and molecules that are sufficiently isolated. Isolated means that they haven't interacted with something that would cause their wave function to collapse. Human Einstein had a hard time accepting it.
If you want to read more about Quantum mechanics read here :- Basics of quantum mechanics. Quantum mechanics explained in easy way ! |Teleportation explained
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