About the MCAT > MCAT Physics

# MCAT Physics

## Vectors and Kinematics

Vectors are quantities that have both a magnitude and a direction. Scalar quantities are quantities which have only a magnitude. So, for example, the information “a Volkswagen Passat is traveling north on the autobahn at 140 km/hour” would be considered a vector quantity because direction (North) and magnitude (speed) are noted, and the information “a Corvette is clocked speeding down I-90 at 150 mph” would be considered a scalar quantity because only the magnitude, or the speed, of the corvette is listed.

Kinematics is the branch of classical mechanics that describes the motion of points, bodies (objects) and systems of bodies (groups of objects) without consideration of the causes of motion. This section will cover trigonometric functions, scalar quantities, vector quantities, and linear motion.

## Forces and Mechanics

Forces and Mechanics are vector quantities experienced by pushing or pulling on force. The magnitude of the force is directly dependent on the mass and the acceleration of the object. A force is directed in a certain direction, such as at a 45 degree angle to the surface of an object, therefore making it a vector quantity. Forces can act with or against each other to affect the total net force on an object. In this section, Newton’s Laws, Free Body Diagrams, circular motion and rotational motion are covered.

## Energy

See Energy

Energy is the capacity of a physical substance to do work. Work is the process by which energy is transferred between systems. There are three types of energy. There is potential energy, which measures the ability to do something. Then there is kinetic energy, which is the energy of motion. Finally, total mechanical energy is the sum of potential and kinetic energy. Everything you may need to know about energy can be found in this section.

## Thermodynamics

Thermodynamics is the study of heat and its relation to energy and work. The Zeroth Law of Thermodynamics states that that there must be a conservation of heat between objects in thermal equilibrium (no net heat exchange, concept of temperature). Temperature is simply the measurement of the kinetic energy an object contains. Everything about thermodynamics including equations relating heat with energy and work are discussed in this section.

## Substances

See Substances

Substances are important to understand their properties and how they behaves in and with their environment. For example, a gas is able to go wide density changes through compression, compared to its liquid or solid forms. A description of the properties and related equations to substance behavior can be found in this section.

## Magnetism

See Magnetism

Magnetism is a branch of physics dealing with the attractive magnetic force between objects has its roots in electric currents and magnetic moments created by elementary particles. These forces will create uniform magnetic field lines, where the magnetic force is equal at all point on the line. Magnetism and the rules for determining the magnitude and direction of a magnetic force are discussed in this section.

## Electrostatics

Electrostatics is a branch of physics that involves the properties and behaviors of stationary or slow moving electric charges with no acceleration. One of the most important laws in this branch is Coulomb’s Law. This law states two things. First, it states that the magnitude of the electrostatic force of interaction between two point charges is directly proportional to the multiplication of the magnitudes of charges and inversely proportional to the square of the distance between the charges. Second, it states that like charges repel and opposite charges attract. This law forms the basis of Electrostatics. Electrostatics and all applicable laws will be discussed in this section.

## Circuits

See Circuits

Circuits are electrical networks consisting of a closed loop, giving a return path for the current. In order to create an electrical current in a circuit, a potential difference must be added somewhere in the circuit. A typical example of a source of potential difference is a battery, where one side is positively charged and the other is negatively charged. Negatively charged electrons move from low potential difference to high potential difference.

Voltage is a measure of this potential difference, i.e. a 9 volt battery has 9 volts of potential difference, which can be converted to coulomb’s a measure of total electrical energy. Therefore, when using 9 volts of potential difference you will always get the same electrical current in the circuit. What happens to this current in the circuit is another story, it depends on whether there are resistors and/or capacitors in the system. Electrical circuits and their components are discussed in this section.

## Motion and Sound

Motion is any movement or change in position or time. Sound is a mechanical wave that is an oscillation of pressure transmitted through a medium such as air or water. These waves must be within the frequency range of the target’s hearing to be detectable. For example, a bat that is nearly blind bounces high frequency sound waves off objects in front of its travel path to detect objects and prey.

The bat can hear this, but if this sound wave were to be captured by the human ear, a human would not detect any sound. Simple Harmonic Motion is repetitive motion of an oscillating system. A mass oscillating about an equilibrium point is subject to a linear restoring force. The force acts to restore the mass to the equilibrium position each time it is displaced. In this section, springs, pendulums, wave forms, strings, and pipes, and their respective equations determining their behavior of motion and/or sound, will be discussed in this section.

## Light and Optics

Light and Optics consist of electromagnetic waves that are radiation which contain of transverse waves created by accelerating electric charges, that oscillate to create electric, and magnetic fields. The fields are perpendicular to each other and to the propagation of the wave. There are many types of magnetic waves, which are defined by their frequency.

There is visible light, which is what we see, there are microwaves which, for example, we cook our food with, there are x-rays, which allow us to better treat bone fractures, and a number of other types of electromagnetic waves. In this section, electromagnetic waves, their behaviors, and the effects of lenses on electromagnetic waves are discussed.

## Atomic Physics

Atomic Physics is the field of physics that studies atoms as an isolated system of electrons and an atomic nucleus. Atomic physics is mostly involved in the study of the arrangement of electrons surrounding the nucleus and the processes by which these arrangements change.

This includes both neutral atoms and ions. The Bohr Model of Hydrogen Atom describes these arrangements as levels of increasing excitement, expressed in increased radii of the electron orbit, known as an orbital. The larger the radius of an orbital, the higher the energy requirement is for an electron to maintain that level. In this section, Atomic Physics, the photoelectric effect, and Bohr’s Atomic Model will be discussed.

## Nuclear Physics

Nuclear Physics is the field of physics that studies the constituents and interactions of atomic nuclei. Various attributes, such as atomic number, atomic mass, isotope, and atomic weight determine the identity and properties of an atom. A major application of nuclear physics is nuclear power. There are two types of nuclear power generation. The first one, and most efficient, is the nuclear fusion reaction, but as of yet remains impractical for power generation for human consumption.

The second, the nuclear fission reaction, involves the splitting of larger isotopes into smaller ones, and has been in use as a power source for decades. The problem with nuclear fission is that it creates radioactive waste products with a long half life, some on the order of thousands of years. Called radioactive decay, as these compounds decompose, they release various radioactive particles, specifically the alpha, beta, and gamma decay particles, and can be extremely hazardous to human health. However, radioactive isotopes can also be used in various applications including the medical field, where it is used to help in the diagnosis of patients and in cancer treatment among other applications. In this section, nuclear physics and radioactive decay will be discussed in detail.