Answer: ballistic trajectory

Question: What space-time path is seen as a curved line in space?


Answer: gravitational force

Context: Since then, and so far, general relativity has been acknowledged as the theory that best explains gravity. In GR, gravitation is not viewed as a force, but rather, objects moving freely in gravitational fields travel under their own inertia in straight lines through curved space-time – defined as the shortest space-time path between two space-time events. From the perspective of the object, all motion occurs as if there were no gravitation whatsoever. It is only when observing the motion in a global sense that the curvature of space-time can be observed and the force is inferred from the object's curved path. Thus, the straight line path in space-time is seen as a curved line in space, and it is called the ballistic trajectory of the object. For example, a basketball thrown from the ground moves in a parabola, as it is in a uniform gravitational field. Its space-time trajectory (when the extra ct dimension is added) is almost a straight line, slightly curved (with the radius of curvature of the order of few light-years). The time derivative of the changing momentum of the object is what we label as "gravitational force".

Question: What is the derivative of an object's changing momentum called?


Answer: global

Question: In what sense must you be observing the curvature of space-time?


Answer: electric current

Context: Through combining the definition of electric current as the time rate of change of electric charge, a rule of vector multiplication called Lorentz's Law describes the force on a charge moving in a magnetic field. The connection between electricity and magnetism allows for the description of a unified electromagnetic force that acts on a charge. This force can be written as a sum of the electrostatic force (due to the electric field) and the magnetic force (due to the magnetic field). Fully stated, this is the law:

Question: What is the time rate of change of electric charge?


Answer: unified electromagnetic

Question: What magnetic and electric force acts on a charge?


Answer: Lorentz's Law

Question: What is the law named that defines a charge moving through a magnetic field?


Answer: electrostatic force

Question: Whatare the electrostatic and magnetic force awritten as the sum of?


Answer: James Clerk Maxwell

Context: The origin of electric and magnetic fields would not be fully explained until 1864 when James Clerk Maxwell unified a number of earlier theories into a set of 20 scalar equations, which were later reformulated into 4 vector equations by Oliver Heaviside and Josiah Willard Gibbs. These "Maxwell Equations" fully described the sources of the fields as being stationary and moving charges, and the interactions of the fields themselves. This led Maxwell to discover that electric and magnetic fields could be "self-generating" through a wave that traveled at a speed that he calculated to be the speed of light. This insight united the nascent fields of electromagnetic theory with optics and led directly to a complete description of the electromagnetic spectrum.

Question: Who first fully explained the origins of magnetic and electric fields?


Answer: 1864

Question: When did the origins of magnetic and electric fields occur?


Answer: 20

Question: How many scalar equations were formed into a set by James Maxwell?


Answer: 4

Question: How many vector equations did Heaviside and Gibbs reformilate Maxwell's 20 scalar equtions into?


Answer: Maxwell

Question: Who discovered that magnetic and electric could self-generate?


Answer: electromagnetic theory

Context: However, attempting to reconcile electromagnetic theory with two observations, the photoelectric effect, and the nonexistence of the ultraviolet catastrophe, proved troublesome. Through the work of leading theoretical physicists, a new theory of electromagnetism was developed using quantum mechanics. This final modification to electromagnetic theory ultimately led to quantum electrodynamics (or QED), which fully describes all electromagnetic phenomena as being mediated by wave–particles known as photons. In QED, photons are the fundamental exchange particle, which described all interactions relating to electromagnetism including the electromagnetic force.[Note 4]

Question: What was dificult to reconcile the photoelectric effect and the missing ultraviolet catastrophe?


Answer: quantum mechanics

Question: What was used to create a new electromagnetic theory to reconcile the troubles with electromagnetic theory as it used to stand?


Answer: quantum electrodynamics

Question: What did electromagnetic theory finally lead to?


Answer: photons

Question: What are the wave-particles called that mediate all electromagnetic phenomena?


Answer: quantum electrodynamics

Question: What is QED short for?


Answer: repulsion of like charges

Context: It is a common misconception to ascribe the stiffness and rigidity of solid matter to the repulsion of like charges under the influence of the electromagnetic force. However, these characteristics actually result from the Pauli exclusion principle.[citation needed] Since electrons are fermions, they cannot occupy the same quantum mechanical state as other electrons. When the electrons in a material are densely packed together, there are not enough lower energy quantum mechanical states for them all, so some of them must be in higher energy states. This means that it takes energy to pack them together. While this effect is manifested macroscopically as a structural force, it is technically only the result of the existence of a finite set of electron states.

Question: What is often misunderstood as the cause of matter rigidity?


Answer: the Pauli exclusion principle

Question: What actually causes rigidity in matter?


Answer: energy

Question: What is needed to pack electrons densely together?


Answer: as a structural force

Question: How is the Pauli exclusion priciple manifested in the macro world?


Answer: repulsion of like charges

Question: What is often misunderstood as the cause of matter rigidity?


Answer: the Pauli exclusion principle

Question: What actually causes rigidity in matter?


Answer: energy

Question: What is needed to pack electrons densely together?


Answer: as a structural force

Question: How is the Pauli exclusion priciple manifested in the macro world?


Answer: elementary particles

Context: The strong force only acts directly upon elementary particles. However, a residual of the force is observed between hadrons (the best known example being the force that acts between nucleons in atomic nuclei) as the nuclear force. Here the strong force acts indirectly, transmitted as gluons, which form part of the virtual pi and rho mesons, which classically transmit the nuclear force (see this topic for more). The failure of many searches for free quarks has shown that the elementary particles affected are not directly observable. This phenomenon is called color confinement.

Question: What does stong force act upon?


Answer: residual of the force

Question: What can be seen between hadrons?


Answer: nuclear

Question: What is the force between nucleons?


Answer: as gluons

Question: How are nuclear forces transmitted?


Answer: color confinement

Question: What is the term for the lack of obsevable free quarks?


Answer: weak force

Context: The weak force is due to the exchange of the heavy W and Z bosons. Its most familiar effect is beta decay (of neutrons in atomic nuclei) and the associated radioactivity. The word "weak" derives from the fact that the field strength is some 1013 times less than that of the strong force. Still, it is stronger than gravity over short distances. A consistent electroweak theory has also been developed, which shows that electromagnetic forces and the weak force are indistinguishable at a temperatures in excess of approximately 1015 kelvins. Such temperatures have been probed in modern particle accelerators and show the conditions of the universe in the early moments of the Big Bang.

Question: What does the W and Z boson exchange create?


Answer: beta decay

Question: What is the observable effect of W and Z boson exchange?


Answer: radioactivity

Question: What is the effect of beta decay?


Answer: 1013

Question: How many times less is the strenght of the weak field compared to the strong?


Answer: approximately 1015 kelvins

Question: At what temperature do weak and electromagnetic forces appear the same?


Answer: normal force

Context: The normal force is due to repulsive forces of interaction between atoms at close contact. When their electron clouds overlap, Pauli repulsion (due to fermionic nature of electrons) follows resulting in the force that acts in a direction normal to the surface interface between two objects.:93 The normal force, for example, is responsible for the structural integrity of tables and floors as well as being the force that responds whenever an external force pushes on a solid object. An example of the normal force in action is the impact force on an object crashing into an immobile surface.

Question: What is the repulsive force of close range atom interaction?


Answer: Pauli repulsion

Question: What occurs when electron clouds overlap from different atoms?


Answer: fermionic nature of electrons

Question: What causes Pauli repulsion?


Answer: normal

Question: What is the force that causes rigid strength in structures?


Answer: ideal strings

Context: Tension forces can be modeled using ideal strings that are massless, frictionless, unbreakable, and unstretchable. They can be combined with ideal pulleys, which allow ideal strings to switch physical direction. Ideal strings transmit tension forces instantaneously in action-reaction pairs so that if two objects are connected by an ideal string, any force directed along the string by the first object is accompanied by a force directed along the string in the opposite direction by the second object. By connecting the same string multiple times to the same object through the use of a set-up that uses movable pulleys, the tension force on a load can be multiplied. For every string that acts on a load, another factor of the tension force in the string acts on the load. However, even though such machines allow for an increase in force, there is a corresponding increase in the length of string that must be displaced in order to move the load. These tandem effects result ultimately in the conservation of mechanical energy since the work done on the load is the same no matter how complicated the machine.

Question: What can be used to model tension forces?


Answer: ideal pulleys

Question: What do you use to let idea strings switch direction?


Answer: action-reaction pairs

Question: In what way do idea strings transmit tesion forces?


Answer: conservation of mechanical energy

Question: What is the final effect of adding more and more idea strings to a load?


Answer: movable pulleys

Question: What can increase the tension force on a load?


Answer: idealized point particles

Context: Newton's laws and Newtonian mechanics in general were first developed to describe how forces affect idealized point particles rather than three-dimensional objects. However, in real life, matter has extended structure and forces that act on one part of an object might affect other parts of an object. For situations where lattice holding together the atoms in an object is able to flow, contract, expand, or otherwise change shape, the theories of continuum mechanics describe the way forces affect the material. For example, in extended fluids, differences in pressure result in forces being directed along the pressure gradients as follows:

Question: What did Newton's mechanics affect?


Answer: three-dimensional objects

Question: What didn't Newton's mechanics affext?


Answer: extended

Question: In what kind of fluid are pressure differences caused by direction of forces over gradients?


Answer: other parts

Question: What may a force on one part of an object affect?


Answer: extended structure

Question: What does matter actually have that Newtonian mechanics doesn't address?


Answer: stress tensor

Context: where is the relevant cross-sectional area for the volume for which the stress-tensor is being calculated. This formalism includes pressure terms associated with forces that act normal to the cross-sectional area (the matrix diagonals of the tensor) as well as shear terms associated with forces that act parallel to the cross-sectional area (the off-diagonal elements). The stress tensor accounts for forces that cause all strains (deformations) including also tensile stresses and compressions.:133–134:38-1–38-11

Question: What causes strain in structures?


Answer: pressure terms

Question: What is used to calculate cross section area in the volume of an object?


Answer: pressure terms

Question: What are associated with normal forces?


Answer: formalism

Question: What includes pressure terms when calculating area in volume?


Answer: rotational equivalent for position

Context: Torque is the rotation equivalent of force in the same way that angle is the rotational equivalent for position, angular velocity for velocity, and angular momentum for momentum. As a consequence of Newton's First Law of Motion, there exists rotational inertia that ensures that all bodies maintain their angular momentum unless acted upon by an unbalanced torque. Likewise, Newton's Second Law of Motion can be used to derive an analogous equation for the instantaneous angular acceleration of the rigid body:

Question: What is the force equivalent of torque compared to angular momentum?


Answer: unbalanced torque

Question: What would change the rotational inertia of a body under Newton's First Law of Motion?


Answer: Newton's Second Law of Motion

Question: To calculate instant angular acceleration of a rigid body what would you use?


Answer: toward the center of the curving path

Context: where is the mass of the object, is the velocity of the object and is the distance to the center of the circular path and is the unit vector pointing in the radial direction outwards from the center. This means that the unbalanced centripetal force felt by any object is always directed toward the center of the curving path. Such forces act perpendicular to the velocity vector associated with the motion of an object, and therefore do not change the speed of the object (magnitude of the velocity), but only the direction of the velocity vector. The unbalanced force that accelerates an object can be resolved into a component that is perpendicular to the path, and one that is tangential to the path. This yields both the tangential force, which accelerates the object by either slowing it down or speeding it up, and the radial (centripetal) force, which changes its direction.

Question: Where does centripetal force go?


Answer: perpendicular

Question: How do centripetal forces act in relation to vectors of velocity?


Answer: centripetal

Question: What force changes an objects direction of travel?


Answer: radial

Question: What is another word for centripetal force?


Answer: tangential force

Question: What is resposible for speeding up or slowing down an object?


Answer: kinetic

Context: A conservative force that acts on a closed system has an associated mechanical work that allows energy to convert only between kinetic or potential forms. This means that for a closed system, the net mechanical energy is conserved whenever a conservative force acts on the system. The force, therefore, is related directly to the difference in potential energy between two different locations in space, and can be considered to be an artifact of the potential field in the same way that the direction and amount of a flow of water can be considered to be an artifact of the contour map of the elevation of an area.

Question: What is the only form potential energy can change into?


Answer: potential

Question: What is the only form kinetic energy can change into?


Answer: net mechanical energy

Question: What is preserved in a closed system of forces when acted upon?


Answer: difference in potential energy

Question: What is the force between two locations related to?


Answer: artifact

Question: What is the force called rgarding a potential field between two locations?


Answer: forces

Context: For certain physical scenarios, it is impossible to model forces as being due to gradient of potentials. This is often due to macrophysical considerations that yield forces as arising from a macroscopic statistical average of microstates. For example, friction is caused by the gradients of numerous electrostatic potentials between the atoms, but manifests as a force model that is independent of any macroscale position vector. Nonconservative forces other than friction include other contact forces, tension, compression, and drag. However, for any sufficiently detailed description, all these forces are the results of conservative ones since each of these macroscopic forces are the net results of the gradients of microscopic potentials.

Question: What is sometimes impossible to model?


Answer: gradient of potentials

Question: Why are some forces due to that are impossible to model?


Answer: friction

Question: What do electrostatic gradiient potentials create?


Answer: Nonconservative

Question: Tension, compression, and drag are what kind of forces?


Answer: statistical mechanics

Context: The connection between macroscopic nonconservative forces and microscopic conservative forces is described by detailed treatment with statistical mechanics. In macroscopic closed systems, nonconservative forces act to change the internal energies of the system, and are often associated with the transfer of heat. According to the Second law of thermodynamics, nonconservative forces necessarily result in energy transformations within closed systems from ordered to more random conditions as entropy increases.

Question: In what treatment are nonconservative and conservative forces described?


Answer: nonconservative forces

Question: What changes macroscopic closed system energies?


Answer: nonconservative forces

Question: What is the exchange of heat associated with?


Answer: Second

Question: What is the law of thermodynamics associated with closed system heat exchange?


Answer: nonconservative forces

Question: What makes energy changes in a closed system?


Answer: kilogram-force

Context: The pound-force has a metric counterpart, less commonly used than the newton: the kilogram-force (kgf) (sometimes kilopond), is the force exerted by standard gravity on one kilogram of mass. The kilogram-force leads to an alternate, but rarely used unit of mass: the metric slug (sometimes mug or hyl) is that mass that accelerates at 1 m·s−2 when subjected to a force of 1 kgf. The kilogram-force is not a part of the modern SI system, and is generally deprecated; however it still sees use for some purposes as expressing aircraft weight, jet thrust, bicycle spoke tension, torque wrench settings and engine output torque. Other arcane units of force include the sthène, which is equivalent to 1000 N, and the kip, which is equivalent to 1000 lbf.

Question: What is the metric term less used than the Newton?


Answer: kilopond

Question: What is the kilogram-force sometimes reffered to as?


Answer: slug

Question: What is a very seldom used unit of mass in the metric system?


Answer: kip

Question: What seldom used term of a unit of force equal to 1000 pound s of force?


Answer: sthène

Question: What is the seldom used force unit equal to one thousand newtons?