Motion diagram

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A motion diagram represents the motion of an object by displaying its location at various equally spaced times on the same diagram. Motion diagrams are a pictorial description of an object's motion. They show an object's position and velocity initially, and present several spots in the center of the diagram. These spots reveal whether or not the object has accelerated or decelerated. [1]

For simplicity, the object is represented by a simple shape, such as a filled circle. It contains information about object positions at particular time instances. Therefore, a motion diagram is more informative than a path.

Viewing Motion Diagrams

One of the major usages of motion diagrams is to present film through a series of frames taken by a camera. Viewing an object on a motion diagram allows one to determine if an object is at a constant rest, speeding up, or slowing down. As the frames are taken, it can be assumed that an object is at a constant rest if it occupies the same position over time. It can be assumed that an object is speeding up if there is a visible increase in the space between objects as time passes. [2] An object can be assumed to be slowing down if there is a visible decrease in the space between objects as time passes. [3] The objects on the frame come very close together.

Related Research Articles

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Force Any action that tends to maintain or alter the motion of an object

In physics, a force is any influence that, when unopposed, will change the motion of an object. A force can cause an object with mass to change its velocity, i.e., to accelerate. Force can also be described intuitively as a push or a pull. A force has both magnitude and direction, making it a vector quantity. It is measured in the SI unit of newton (N). Force is represented by the symbol F.

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Mechanics is the area of physics concerned with the motions of physical objects, more specifically the relationships among force, matter, and motion. Forces applied to objects result in displacements, or changes of an object's position relative to its environment. This branch of physics has its origins in Ancient Greece with the writings of Aristotle and Archimedes. During the early modern period, scientists such as Galileo, Kepler, and Newton laid the foundation for what is now known as classical mechanics. It is a branch of classical physics that deals with particles that are either at rest or are moving with velocities significantly less than the speed of light. It can also be defined as a branch of science which deals with the motion of and forces on bodies not in the quantum realm. The field is today less widely understood in terms of quantum theory.

Special relativity Theory of interwoven space and time by Albert Einstein

In physics, the special theory of relativity, or special relativity for short, is a scientific theory regarding the relationship between space and time. In Albert Einstein's original treatment, the theory is based on two postulates:

  1. The laws of physics are invariant in all inertial frames of reference.
  2. The speed of light in vacuum is the same for all observers, regardless of the motion of the light source or observer.
Speed of light Speed at which all massless particles and associated fields travel in vacuum

The speed of light in vacuum, commonly denoted c, is a universal physical constant important in many areas of physics. Its exact value is defined as 299792458 metres per second. It is exact because, by international agreement, a metre is defined as the length of the path travelled by light in vacuum during a time interval of 1299792458 second. According to special relativity, c is the upper limit for the speed at which conventional matter, energy or any signal carrying information can travel through space.

Spacetime Mathematical model combining space and time

In physics, spacetime is any mathematical model which fuses the three dimensions of space and the one dimension of time into a single four-dimensional manifold. Spacetime diagrams can be used to visualize relativistic effects, such as why different observers perceive differently where and when events occur.

Twin paradox Thought experiment in special relativity

In physics, the twin paradox is a thought experiment in special relativity involving identical twins, one of whom makes a journey into space in a high-speed rocket and returns home to find that the twin who remained on Earth has aged more. This result appears puzzling because each twin sees the other twin as moving, and so, as a consequence of an incorrect and naive application of time dilation and the principle of relativity, each should paradoxically find the other to have aged less. However, this scenario can be resolved within the standard framework of special relativity: the travelling twin's trajectory involves two different inertial frames, one for the outbound journey and one for the inbound journey. Another way of looking at it is by realising that the travelling twin is undergoing acceleration, which makes him a non-inertial observer. In both views there is no symmetry between the spacetime paths of the twins. Therefore, the twin paradox is not a paradox in the sense of a logical contradiction.

In physics, a frame of reference consists of an abstract coordinate system and the set of physical reference points that uniquely fix the coordinate system and standardize measurements within that frame.

Principle of relativity Physics principle stating that the laws of physics must be the same in all reference frames

In physics, the principle of relativity is the requirement that the equations describing the laws of physics have the same form in all admissible frames of reference.

Angular frequency

In physics, angular frequencyω is a scalar measure of rotation rate. It refers to the angular displacement per unit time or the rate of change of the phase of a sinusoidal waveform, or as the rate of change of the argument of the sine function. Angular frequency is the magnitude of the vector quantity angular velocity.

Galilean invariance or Galilean relativity states that the laws of motion are the same in all inertial frames. Galileo Galilei first described this principle in 1632 in his Dialogue Concerning the Two Chief World Systems using the example of a ship travelling at constant velocity, without rocking, on a smooth sea; any observer below the deck would not be able to tell whether the ship was moving or stationary.

Length contraction Contraction of length in the direction of propagation in Minkowski space

Length contraction is the phenomenon that a moving object's length is measured to be shorter than its proper length, which is the length as measured in the object's own rest frame. It is also known as Lorentz contraction or Lorentz–FitzGerald contraction and is usually only noticeable at a substantial fraction of the speed of light. Length contraction is only in the direction in which the body is travelling. For standard objects, this effect is negligible at everyday speeds, and can be ignored for all regular purposes, only becoming significant as the object approaches the speed of light relative to the observer.

Gravitational time dilation Form of time dilation

Gravitational time dilation is a form of time dilation, an actual difference of elapsed time between two events as measured by observers situated at varying distances from a gravitating mass. The lower the gravitational potential, the slower time passes, speeding up as the gravitational potential increases. Albert Einstein originally predicted this effect in his theory of relativity and it has since been confirmed by tests of general relativity.

Relativity of simultaneity Concept that distant simultaneity is not absolute, but depends on the observers reference frame

In physics, the relativity of simultaneity is the concept that distant simultaneity – whether two spatially separated events occur at the same time – is not absolute, but depends on the observer's reference frame.

Expansion of the universe Increase in distance between parts of the universe over time

The expansion of the universe is the increase in distance between any two given gravitationally unbound parts of the observable universe with time. It is an intrinsic expansion whereby the scale of space itself changes. The universe does not expand "into" anything and does not require space to exist "outside" it. Technically, neither space nor objects in space move. Instead it is the metric governing the size and geometry of spacetime itself that changes in scale. As the spatial part of the universe's spacetime metric increases in scale, objects move apart from one another at ever-increasing speeds. To any observer in the universe, it appears that all of space is expanding while all but the nearest galaxies recede at speeds that are proportional to their distance from the observer – at great enough distances the speeds exceed even the speed of light.

Spacetime diagram

A spacetime diagram is a graphical illustration of the properties of space and time in the special theory of relativity. Spacetime diagrams allow a qualitative understanding of the corresponding phenomena like time dilation and length contraction without mathematical equations.

Classical mechanics branch of physics concerned with the set of classical laws describing the non-relativistic motion of bodies under the action of a system of forces

Classical mechanics is a physical theory describing the motion of macroscopic objects, from projectiles to parts of machinery, and astronomical objects, such as spacecraft, planets, stars, and galaxies. For objects governed by classical mechanics, if the present state is known, it is possible to predict how it will move in the future (determinism), and how it has moved in the past (reversibility).

Time in physics

Time in physics is defined by its measurement: time is what a clock reads. In classical, non-relativistic physics, it is a scalar quantity and, like length, mass, and charge, is usually described as a fundamental quantity. Time can be combined mathematically with other physical quantities to derive other concepts such as motion, kinetic energy and time-dependent fields. Timekeeping is a complex of technological and scientific issues, and part of the foundation of recordkeeping.

In physics, the history of centrifugal and centripetal forces illustrates a long and complex evolution of thought about the nature of forces, relativity, and the nature of physical laws.

References

  1. Bonham, Scott. (unknown year). Motion diagrams. Manuscript submitted for publication, Department of Physics, Western Kentucky University, Bowling Green, KY. Retrieved from http://webphysics.davidson.edu/physlet_resources/western_kentucky/MotionDiagrams.html
  2. Knight, R. (2008). Physics for scientists and engineers: a strategic approach. San Francisco, CA: Pearson Education Inc.
  3. Knight, R. (2008). Physics for scientists and engineers: a strategic approach. San Francisco, CA: Pearson Education Inc.