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Physics is a branch of Science that deals with the nature and properties of matter and energy. The subject matter of physics includes mechanics, heat, light and other radiation, sound, electricity, magnetism, and the structure of atoms.
The five major branches of physics are: The Classical mechanics. Statistical mechanics and Thermodynamics. Electronics and Electromagnetism. The Relativity theory. Quantum mechanics. Physics as a subject includes 1. Work, Force and Energy 2. Dynamics & Laws of Motion 3. Circular motion and gravitation 4. Linear Momentum and Collisions 5. Statics and Torque 6. Rotational Motion and Angular Momentum 7. Electricity and Magnetism 8. Electromagnetic Induction, AC Circuits 9. Electromagnetic Waves 10. Optics and Vision 11. Atomic Physics 12. Quantum Physics 13. Relativity and particle Physics 14. Temperature, Kinetic Theory, and the Gas Laws 15. Heat and Thermodynamics 16. Oscillatory Motion and Waves 17. Sound and physics of hearing 18. Statics and Torque 19. Thermodynamics
1. Work, Force and Energy
Define Work Work is the amount of energy transferred to an object by an external force when it is moved over a certain distance by that force. Work done = Force X Displacement Let us say we applied 20 unit force on an object, and it moved 6 units Work Done = 20X6 =120 In this example, suppose we are unable to move object does not matter how big force we applied work done will be zero according to physics Work Done = Force (does not matter how big) X 0 = 0 Define Force A force is a push or pull upon an object resulting from the object's interaction with another object. Define Energy Energy is defined as the “ability to do work. In other words energy is just the force that causes things to move. Energy is divided into two types: potential and kinetic.
2. Dynamics & Laws of Motion
Dated August 28,2023 6:14 PM Dynamics and Laws of Motion Define Dynamics Dynamics is the branch of mechanics concerned with the motion of bodies under the action of forces. Dynamics is the study of how moving objects behave. Dynamics is the part of mechanics that studies movement and its causes. The study of the causes of motion and changes in motion is known as dynamics. Dynamics is the study of how moving objects behave Newton's first law Newton's first law also called law of inertia Any object remains at a state of rest or of motion in a straight line at constant speed unless it is acted upon by a force. Example : Amrik will stay on his chair unless attracted by or repelled by some person - laugh out loud. Jokes aside, let us know more Reference https://byjus.com/physics/laws-of-motion/ In “Law of Inertia,” Newton highlighted this inherent property of objects and laid the groundwork for understanding how forces can cause changes in motion. Newton’s first law of motion states that objects persist in their current state of motion unless compelled to do otherwise by an external force. Whether an object is at rest or in uniform motion, it will continue in that state unless a net external force acts upon it.
Newton's Second Law of Motion In Simple words, Newton's second law states the acceleration of an object is directly proportional to the net external force applied, and it is indirectly proportional to its mass. In other words, more force generates more acceleration for a given mass, but more mass means less acceleration from a given force. F= ma Where "F" is Force Applied Where "m" is the mass of the object and "a" stands for acceleration To understand acceleration, it is gaining speed Acceleration definition: acceleration, rate at which velocity changes with time, in terms of both speed and direction. A point or an object moving in a straight line is accelerated if it speeds up or slows down. Motion on a circle is accelerated even if the speed is constant, because the direction is continually changing. if we a=F/m now we can see from this equation that acceleration is directly proportional to the force which means larger the force greater the acceleration and acceleration is inversely proportional to the mass of the object which means larger the mass lesser the acceleration
Newton's Third Law of Motion Newton's third law states that every action has an equal and opposite reaction. Example : You pull the tail of a lion, the loud roar you hear is opposite reaction - laugh out slowly because this does not fit in newton's law roar may not be equal reaction it could be way more than that.🙏😂. Jokes aside we always read the example when you pull trigger of a gun your shoulder get back push. Other examples are 1. Pulling an elastic band. 2. Swimming or rowing a boat. 3. Static friction while pushing an object. 4. Walking. 5. Slingshot. Swing is a good example, we push the swing to one side, and it swings by equal distance to the opposite side.
Dynamics is the study of forces and motion. More formally, dynamics is the branch of mechanics that deals with the effect that forces have on the motion of objects. In contrast, statics is the study of forces without motion; or more formally, the branch of mechanics that deals with forces in the absence of changes in motion. Dynamics implies change. Statics implies changelessness. The change that matters is acceleration.
Define Momentum -the quantity of motion of a moving body, measured as a product of its mass and velocity. Momentum can be defined as "mass in motion." All objects have mass; so if an object is moving, then it has momentum - it has its mass in motion. p = mv p = momentum m = mass v = velocity How to understand momentum. Think about two vehicles running at the same speed but different mass. The one that have larger mass has greater momentum because momentum is the product of mass and velocity.
3. Circular Motion and Gravitation
Credits Google Search Engine Circular motion is described as a movement of an object while rotating along a circular path. Circular motion can be either uniform or non-uniform. During uniform circular motion, the angular rate of rotation and speed will be constant, while during non-uniform motion the rate of rotation keeps changing. What are examples of circular motion? Examples of circular motion are carousels or merry-go-rounds in parks, a car going around a roundabout, the moon orbiting around the Earth or the Earth revolving around the Sun. What are the properties of circular motion? Characteristics of Circular Motion: In a circular motion, the particle moves along the circumference of a circle. It is a translational motion along a curved path. The magnitude of the radius vector or position vector is constant and equals to the radius of the circular path. What keeps an object in circular motion? A centripetal force is a net force that acts on an object to keep it moving along a circular path. What is the law of motion for circular motion? The direction of a centripetal force is toward the center of rotation, the same as for centripetal acceleration. According to Newton's second law of motion, a net force causes the acceleration of mass according to Fnet = ma. For uniform circular motion, the acceleration is centripetal acceleration: a = ac. What is the difference between rotational motion and circular motion? Rotational motion is based around the idea of rotation of a body about its center of mass. In rotational motion, the axis of rotation and Centre of mass could change whereas in circular motion, the axis of rotation and Centre of mass does not change. Picture Creative commons. Credits Wikipedia
Dated September 06,2023 3:29 AM Laws of Gravitation Newton's law of gravitation, statement that any particle of matter in the universe attracts any other with a force varying directly as the product of the masses and inversely as the square of the distance between them.
Isaac Newton's 1687 description of gravity was considered scientific law until Einstein's General Theory of Relativity, published more than two centuries later. Newton's law has later been superseded by Albert Einstein's theory of general relativity, but the universality of the gravitational constant is intact, and the law still continues to be used as an excellent approximation of the effects of gravity in most applications.
What is the second law of gravity? Newton's second law states that the net external force acting on an object is responsible for the acceleration of the object. If air resistance is negligible, the net external force on a falling object is only the gravitational force (i.e., the weight of the object)Newton proved that the force that causes, for example, an apple to fall toward the ground is the same force that causes the moon to fall around, or orbit, the Earth. This universal force also acts between the Earth and the Sun, or any other star and its satellites. Each attracts the other
How is gravitation different from gravity? The major difference between gravitation and gravity is that gravitational force occurs between two different or the same objects. While the force of gravity acts between the earth surface and any object. The force of gravitation acting between two objects is quite weaker as compared to the force of gravity.
The forces it describes are real ones, not mere bookkeeping devices. For example, a book resting on a table applies a downward force equal to its weight on the table. According to the third law, the table applies an equal and opposite force to the book.
4. Linear Momentum and Collisions
Define Momentum Linear Momentum Linear momentum is defined as the product of a system’s mass multiplied by its velocity. In symbols, linear momentum is expressed as p = mv. A common understanding of momentum is: a large, fast-moving object has greater momentum than a smaller, slower object. The importance of momentum Momentum was deemed so important that it was called the “quantity of motion.” Newton stated his second law of motion in terms of momentum: The net external force equals the change in momentum of a system divided by the time over which it changes. F net = Δp/ Δt where Fnet is the net external force, Δp is the change in momentum, and Δt is the change in time.
Mometum
Collision in Physics
What are the 3 collisions in physics? There are three types of collisions as follows: 1. Perfectly elastic collision. 2. Inelastic collision. 3. Perfectly inelastic collision.
1. Perfectly elastic collision When two bodies collide but there is no loss in the overall kinetic energy, it is called a perfectly elastic collision.In elastic collisions, the kinetic energy and momentum of the system remains conserved. In elastic collision, the colliding objects bounce apart and do not stick together. Examples include Ping-pong ball,Hitting the Marbles,Newton's Cradle,Carrom board carroms,Trampoline.
2. Inelastic Collision An inelastic collision is such a type of collision that takes place between two objects in which some energy is lost. In the case of inelastic collision, momentum is conserved but the kinetic energy is not conserved. Most of the collisions in daily life are inelastic in nature m1v1+m2v2 = (m1+m2)Vf Where m1 is mass of object one and v1 is initial velocity of object one. M2 is mass of object two ,v2 is intial velocity of object two and Vf is final velocity of objects
3. Perfectly Inelastic collision An inelastic collision is one in which kinetic energy is not conserved. A perfectly inelastic collision is one in which objects stick together after impact, and the maximum amount of kinetic energy is lost. For example, when a wet mudball is thrown against a wall, the mudball sticks to the wall
5. Statics and Torque
What is torque in simple terms Torque is a twisting force. Imagine you have a bolt with a nut on it and you want to unscrew the nut with a wrench. You put the wrench on the nut and apply a certain amount of force to loosen it. The force generated there is called torque. Torque = R F sin θ R = radius (Length of arm from point of rotation to the edge) F = Force Theeta θ = angle between F and the lever arm
Updated October 09,2023
7. Electricity and Magnetism
Electricity and magnetism are closely related. Flowing electrons produce a magnetic field, and spinning magnets cause an electric current to flow.Electricity can be present in a static charge, while magnetism’s presence is only felt when there are moving charges as a result of electricity. In simple words, electricity can exist without magnetism, but magnetism cannot exist without electricity.
Electricity and magnetism are essentially two aspects of the same thing, because a changing electric field creates a magnetic field, and a changing magnetic field creates an electric field. (This is why physicists usually refer to “electromagnetism” or “electromagnetic” forces together, rather than separately.)
Before I jump to magnetic effects of current, let us know how electricity flows through a circuit. It could be compared with water tank, water tank is always placed higher than the tap. Water flows from water tank to tap. Similarly electricity flows from higher potential to lower potential. The direction of motion of positive charge is always high potential to low potential but direction of motion of negative charge is always from low potential to high potential. So we can say that current flows the same as direction of field and high potential to low potential. For example if two terminals have 24 Volt and 6 Volt Current will flow from the terminal at 24V potential to the terminal at 6 V potential. Generally it is Terminal one 12 V and Terminal two 0 V for common DC applications. I mentioned these examples to clarify the basics. For example if Terminal one is at 0 Volt potential and terminal two is at -12 Volt potential. The current will flow from 0V terminal to -12 Volt terminal.
There are three effects of Current 1. Heating effect of current - (All electric heaters are designed on based of this effect of current) Heat produced is equal to i²rt where i is current in amperes, r is resistance value in ohm and t is time in seconds 2. Magnetic effects of currents - ( All Relays, Motors and drives are designed based on this effect of current) We will discuss this in detail right after this third effect. 3. Chemical effects of current - ( All Electroplating - Electroplating is a process for producing a metal coating on a solid substrate through the reduction of cations of that metal by means of a direct electric current, and Batteries use this principle)
Magnetic effects of Current
Magnetic Effect of Electric Current – A magnetic field is a force field that is created by moving electric charges, and it exerts a force on other nearby moving charges. Magnetic Field is a vector quantity because it has both magnitude and direction.+ Right Hands Thumb Rule can help understand magnetic field produced around current carrying conductor. The magnetic field made by a current in a straight wire curls around the wire in a ring. You can find it by pointing your right thumb in the direction of the current in the wire and curling your fingers. Your fingers will be curled in the same direction as the magnetic field around
This illustration explains magnetic effects of current as well as how basic DC motor works
Magnetic Effect of Electric Current A daily life example that is based on this principle of Magnetic effects of current is doorbell. The heart of a doorbell is an electromagnet. Electromagnets are coils of wire wrapped around a small piece of metal. When electricity passes through the wire, it creates a magnetic field around the wire. When you press a doorbell button, you complete an electrical circuit that allows household electricity to flow through the doorbell's internal electromagnet. The magnetic field generated by the electromagnet pulls a piece of metal like piston and then release it. Spring loaded piston hits the piece of metal and the doorbell sound. Doorbells are low-voltage devices. This means they require relatively little energy to operate. An important part of a doorbell mechanism is the transformer. The transformer converts regular 120-volt household current to the lower voltage (usually somewhere between 6-16 volts) required by the doorbell. In the following picture you can see two bolt like pistons one of them is activated by front door push switch and the second is activated by side door (or Rear Door) push button. They have two different sounds to identify which door button the guest hits.
To further make the concept clear please watch this video.
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