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# Scientific Review of The Cartoon Guide to Physics

I read this book called, “The Cartoon Guide to Physics.” In this book, the author explains how the law of physics work and the cartoonist gives a visual explanation which helped me understand how the equation works since I’m a visual person. This paper is about a book titled “The Cartoon Guide to Physics.” This book explains complicated physics equations using cartoons. This approach helped me a great deal because I understand things better if I can picture them in my mind. This book was very good for me because I could see the equation and read it at the same time which is very helpful.

This book talked about all kinds of problems and situations used in the study of physics. Almost everything on this earth revolves around physics. Examples of Motion like birds flying, trees falling, and this world revolving. The whole universe is in motion.

Because of this book, I understood the law of motion and the equation, which this book gave an example of, such as D=V(T). D= for distance, V=for Velocity (speed), and T= for Time. The author explains this by using the motion of a car. I also understood the concepts of how “natural” motion of Celestial objects like the moon and stars was Circular, while Terrestrial objects like apples, rocks, and I tend “naturally” to fall down. If the moon naturally moves in a circle, we don’t need any gravity to explain its motion. But when earthly objects fall, it comes to rest unless some force pushes them sideways. Galileo claims that no force is needed to keep an object in a uniform, straight-line motion. Things cannot travel in a straight line forever because the force of friction slows it down. Isaac Newton summarized Galileo’s idea. Newton’s First Law: an object at rest tends to stay at rest. An object in motion tends to continue in motion at a constant speed in a straight line. This means that if there were no forces, objects would move with constant velocity.

Newton’s Second law: F=m(a), the more force on an object, the more it accelerates. But the more massive it is, the more it resists acceleration. This means that if I push a grocery cart with a lot of force, the faster the cart would go. But if I try to push a building, the building would not move because it has more mass then I have so it will resist acceleration.

Newton’s Third Law: When one object exerts a force on a second object, the second object exerts an equal but opposite force on the first. Let me give you an example of Newton’s Third Law. When I push on a wall, the wall pushes back with equal force. The earth’s gravitational pull on the moon equals the moon’s pull on the earth. The earth’s pull on the moon keeps the moon in a nearly circular orbit. The moon pulling back with equal force does cause the earth to execute a small orbit. The earth moves less than the moon and accelerates less because it is much more massive. Another example: A rocket engine. The rocket exerts a downward push on the exhaust gases. The gases push back, by Newton’s third law. If this upward thrust exceeds the weight of the vehicle, we will go up. Newton’s Laws can be thought of as describing what forces do:

1. Without any forces, objects maintain a constant velocity.
2. A force produces an acceleration proportional to the force and inversely proportional to the mass.
3. An object exerts equal but opposite forces on each other.

More examples of forces: Force is a “Vector Quantity.” Like velocity and acceleration, it has only a magnitude but also a direction. Consider the forces on a skier moving down a hill at a constant speed. They are her weight, the support of the ground, and the force of friction. But again, the total force must

Be zero. One force that we encounter every day is Friction. If I push a book across the table, I find that friction resists, whatever direction I push. If I started pushing gently, I’ll find that the friction force is variable.

The four basic forces are gravity, electromagnetism, the subatomic weak force, and the strong force holding the atomic nucleus together. I found out that the only one of the four basic forces I’ll ever feel is electromagnetism. Like when I push the wall and it pushes back, I’m feeling electric repulsion between atoms.

I didn’t understand the Physics laws about Projectiles at first, but once I read the example and observed the cartoons, it became clearer to me. “The simplest projectile motion is to project something sideways: driving a car off a cliff or shooting a bullet horizontally. The key to understanding this motion is to realize that gravity acts only vertically. It affects only the downward part of the motion.” This statement made it so much clearer for me to understand how projectile works. The only bad thing is that if someone gives me a problem or situation having to deal with projectiles, I don’t think I could solve the problem but at least I understand the concept of it.

Another example of a situation which I’m having a hard time comprehending is the question of, “what would happen if we projected it with a different speed, or at another space?” This book explains this question by using a technique known as “Brute Force.” The Brute-Force method starts with the gravitational formula: F=G(Mm/r^2), M=mass of earth; m=mass of a satellite; r=distance between them; G= constant. The formula gives the force on the satellite, so we can compute its acceleration by Newton’s second law(a=F/m). Then we can compute how much its velocity changes, owing to this acceleration. If someone gave me a type of problem having to use the Brute-Force method, I’m more likely now going to be excellent at solving it.

In my opinion, the best subject in this book was the topic of “Energy.” Isaac Newton almost single-handedly invented the science of mechanics, but he missed the concept of Energy. Energy comes in many forms, but the basic definition is the terms of Work. The definition of work in physics is very precise. In physics, they say that work is done when a force moves a body through a distance. Work is defined as Force times Distance (W=F(d)). In this definition, only the force in the direction of movement counts. If I pull a wagon at an angle, only the horizontal part of the pull does any work. If I whirl a ball on a string at a constant speed, again no work is done. The inward force is always perpendicular to the (Tangential) velocity of the ball. But, I do have to do some work to start it whirling in the first place.

Energy is defined as the capacity to do work. The release of energy does work and doing work on something adds energy to it. So energy and work are actually the same concepts: E=W=F(d).

Now I’ll turn to the subject of electricity and magnetism. In electricity, the basic concept is “Charge.” It is easy to produce a little charge. We just have to run a rubber comb through our hair, or rub a rubber rob with animal fur. Placing the charged rod n a hanging stirrup and bringing another, similarly a charged rod near, they repel. But if we rub a plastic rob and silk, it attracts the rubber rob. Benjamin Franklin named the two kinds of charges “Positive” and “Negative.” We now know that all matter is made of atoms, which are composed of negatively charged electrons, whirling around a nucleus of positively charged protons, and neutrons, which have no charge. Electrons and Protons have equal and opposite charges. Normal atoms have exactly enough electrons to balance the protons in the nucleus, making the atom overall neutral. When an electron is removed from an atom, the atom becomes a positively charged Ion. In an Electrical force grows weaker with distance. I learned that materials like rubber, glass, and plastic are electrical insulators: Charges can be rubbed on or off their surfaces, but it tends to stick there and will not move easily through the materials. But in metals, like copper, silver, and aluminum, the electrons can move around freely and easily. Metals are electrical conductors.

What we call “electricity” is just a flow of electrons. Lets switch the subject to magnetic fields. I learned that several years ago, the Greeks, discovered that certain metallic rocks from the district of Magnesia in Asia minor would attract ions, and attract or repel similar rocks. The further study established that magnets always have two Poles, called North and South. If you allow a magnet to pivot, its North pole is the one that points toward the Earth’s (geographic) North. A compass is just a magnetic needle on a pivot.

Up until the year of 1820, everyone thought magnetism and electricity were completely separate. But in that year, the Danish Physicist Hans Oersted discovered that a compass needle was deflected by electric current.

First, if the charge is not moving, there is no force. And there is no force if the charge is moving along a field line, but if the charge is moving across the field line, it feels something. The force on the charge is a “Sideways” force perpendicular to both the field line and the charge’s velocity. Magnetic fields produce forces on moving charged particles. The forces are perpendicular to both the velocity of the particle and the direction of the magnetic field. To examine the simplest case, let a current-carrying wire go straight through a plane covered with compass needles. The needles line up in circles around the wire. The magnetic field of a current is circles centred on the wire and lying in the plane perpendicular to the current.

Those are all the examples and subjects I learned from this book. Well, actually I didn’t state all the subjects that I learned. I only included the ones I’m particularly fond of. I really enjoyed learning more about physics and how the thing works and I recommend this book to anyone who would like to learn about physics but has a hard time understanding it.