# Model of motion physics

Momentum is a commonly used term in sports. A team that has the momentum is on the move and is going to take some effort to stop. A team that has a lot of momentum is really on the move and is going to be hard to stop. Momentum is a physics term; it refers to the quantity of motion that an object has. A sports team that is on the move has the momentum. If an object is in motion on the move then it has momentum.

Momentum can be defined as "mass in motion. The amount of momentum that an object has is dependent upon two variables: how much stuff is moving and how fast the stuff is moving. Momentum depends upon the variables mass and velocity. In terms of an equation, the momentum of an object is equal to the mass of the object times the velocity of the object. In physics, the symbol for the quantity momentum is the lower case p.

Thus, the above equation can be rewritten as. The equation illustrates that momentum is directly proportional to an object's mass and directly proportional to the object's velocity. The units for momentum would be mass units times velocity units.

### Collective model

In each of these examples, a mass unit is multiplied by a velocity unit to provide a momentum unit. This is consistent with the equation for momentum. Momentum is a vector quantity. As discussed in an earlier unit, a vector quantity is a quantity that is fully described by both magnitude and direction. The direction of the momentum vector is the same as the direction of the velocity of the ball.

In a previous unit, it was said that the direction of the velocity vector is the same as the direction that an object is moving. As a vector quantity, the momentum of an object is fully described by both magnitude and direction.

From the definition of momentum, it becomes obvious that an object has a large momentum if both its mass and its velocity are large. Both variables are of equal importance in determining the momentum of an object. Consider a Mack truck and a roller skate moving down the street at the same speed. The considerably greater mass of the Mack truck gives it a considerably greater momentum. Yet if the Mack truck were at rest, then the momentum of the least massive roller skate would be the greatest.

The momentum of any object that is at rest is 0. Objects at rest do not have momentum - they do not have any " mass in motion.I completely blame Dan Fullerton aplusphysics.

He said it would be cool to use this Kerbal Space Program in physics. Here are his details on this idea. The Kerbal Space Program is a space simulator that runs on your computer. It looks really cool, but I didn't play with it.

Instead I wanted to see if they had something like this for phones. Yup, they do. It's called Space Agency - iTunes link. Although it's a fun game, I had problems with it at first because it doesn't follow real world physics. I don't mean that I didn't like the game. I mean I had a problem - I couldn't do one of the levels. In one mission, you have to dock with another object in orbit. For your own spacecraft, you can turn and thrust. This means you can use the rocket thrust to push your spacecraft either tangent to your orbital path or perpendicular.

## Types of Motion With Examples in Physics

Here is the problem. When you thrust tangent to the orbital path, your spacecraft moves faster but stays at the same orbital radius. When you thrust perpendicular to the path, your spacecraft changes its orbital radius, but not the speed. Although this makes navigation in orbit a bit simpler, it isn't what I expected. Let's say I have an object in orbit around the Earth. There are two, well maybe three important ideas. The gravitational force is an interaction between objects with mass.

The farther away the objects get, the lower in magnitude the gravitational force becomes.

Equations of Motion (Physics)

I can model the magnitude of the gravitational forces as:. In this model, G is the gravitational constant. M and m are the masses of the two objects I will let the Earth's mass be M and r is the distance between the centers of the objects if you assume they are spherically symmetric. Or, the total vector force on an object is equation to the time-rate of change of its vector momentum.

Basically, forces change the momentum of an object. In this case, we can say that the vector momentum is the product of mass and vector velocity. The last thing is the change in momentum for an object moving in a circle like a circular orbit.

If it is moving with a constant speed in a circle, the magnitude of the change in vector momentum would be:. R is the radius of the circle. If you like to look at this in terms of the speed of the object, v is the magnitude of the velocity.A body is said to be in Motion if it changes its position with respect to its surroundings.

Basically, there are three Types of Motion, Translatory motion, Rotatory motion, and Vibratory motion. Surroundings are the places in their neighborhood where various objects are present. The state of rest or motion of a body is relative. For example, a passenger sitting in a moving bus is at rest because he is not changing his position with respect to other passengers or objects on the bus. But to an observer outside the bus, the passengers and the objects inside the bus are in motion.

We live in a universe of continual motion. In every piece of matter, the atoms are in the state of never-ending motion. The sun and the stars, too, are in motion. Everything in the vastness of space is in a state of perpetual motion. Every physical process involves the movement of some sort. Because of its importance in the physical world around us.

It is logical that we should give due attention to the study of motion. Motion is commonly described in terms of:. If we observe carefully, we will find that everything in the universe is in motion. However, different objects move differently.

Some objects move along a straight line, some move in a curved path, and some move in some other way. According to this, we can say that there are three types of motion. Which are given as:. The line may be straight or curved. Do they move along a straight line? Do they move along a circle?

A car moving in a straight line has transnational motion. Similarly, an airplane moving straight is in translational motion. Translatory motion is further divided into linear motion, circular motion and random motion. Learn more about: Difference between uniform and non uniform motion. We come across many objects which are moving in a straight line. The motion of objects such as car moving on a straight and level road is linear motion. Airplanes flying straight in air and objects falling vertically down are also the examples of linear motion. Earth revolving around the sun is an example of circular motion.

A bicycle or a car moving along a circular track possesses circular motion. The motion of the moon around the earth is also an example of circular motion. Their movements are irregular and disorder. The motion of insects and birds is random motion.

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The motion of dust or smoke particles in the air is also random motion. The Brownian motion of a gas or liquid molecules along a zig-zag is also an example of random motion. Study the motion of a tap. It is spinning about an axis.Projectile motion is a form of motion experienced by an object or particle a projectile that is projected near the Earth's surface and moves along a curved path under the action of gravity only in particular, the effects of air resistance are assumed to be negligible.

This curved path was shown by Galileo to be a parabolabut may also be a line in the special case when it is thrown directly upwards. The study of such motions is called ballisticsand such a trajectory is a ballistic trajectory. The only force of significance that acts on the object is gravity, which acts downward, thus imparting to the object a downward acceleration.

Because of the object's inertiano external horizontal force is needed to maintain the horizontal velocity component of the object. Taking other forces into account, such as friction from aerodynamic drag or internal propulsion such as in a rocketrequires additional analysis. A ballistic missile is a missile only guided during the relatively brief initial powered phase of flight, and whose subsequent course is governed by the laws of classical mechanics.

Ballistics gr. The elementary equations of ballistics neglect nearly every factor except for initial velocity and an assumed constant gravitational acceleration. Practical solutions of a ballistics problem often require considerations of air resistance, cross winds, target motion, varying acceleration due to gravity, and in such problems as launching a rocket from one point on the Earth to another, the rotation of the Earth. Detailed mathematical solutions of practical problems typically do not have closed-form solutions, and therefore require numerical methods to address.

In projectile motion, the horizontal motion and the vertical motion are independent of each other; that is, neither motion affects the other. This is the principle of compound motion established by Galileo in and used by him to prove the parabolic form of projectile motion . A ballistic trajectory is a parabola with homogeneous acceleration, such as in a space ship with constant acceleration in absence of other forces.

This causes an elliptic trajectory, which is very close to a parabola on a small scale. However, if an object was thrown and the Earth was suddenly replaced with a black hole of equal mass, it would become obvious that the ballistic trajectory is part of an elliptic orbit around that black hole, and not a parabola that extends to infinity. At higher speeds the trajectory can also be circular, parabolic or hyperbolic unless distorted by other objects like the Moon or the Sun. In this article a homogeneous acceleration is assumed.

The vertical motion of the projectile is the motion of a particle during its free fall.

## Collective model

Here the acceleration is constant, being equal to g. The horizontal component of the velocity of the object remains unchanged throughout the motion. The vertical component of the velocity changes linearly,  because the acceleration due to gravity is constant. The accelerations in the x and y directions can be integrated to solve for the components of velocity at any time tas follows:.

The magnitude of the velocity under the Pythagorean theoremalso known as the triangle law :. This is the equation of a parabola, so the path is parabolic. The axis of the parabola is vertical.

The total time t for which the projectile remains in the air is called the time of flight. If the starting point is at height y 0 with respect to the point of impact, the time of flight is:.

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The greatest height that the object will reach is known as the peak of the object's motion. The range and the maximum height of the projectile does not depend upon its mass. Hence range and maximum height are equal for all bodies that are thrown with the same velocity and direction. According to the work-energy theorem the vertical component of velocity is:.

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These formulae ignore aerodynamic drag and also assume that the landing area is at uniform height 0.Collective modelalso called unified modeldescription of atomic nuclei that incorporates aspects of both the shell nuclear model and the liquid-drop model to explain certain magnetic and electric properties that neither of the two separately can explain. In the shell model, nuclear energy levels are calculated on the basis of a single nucleon proton or neutron moving in a potential field produced by all the other nucleons.

Nuclear structure and behaviour are then explained by considering single nucleons beyond a passive nuclear core composed of paired protons and paired neutrons that fill groups of energy levels, or shells. In the liquid-drop modelnuclear structure and behaviour are explained on the basis of statistical contributions of all the nucleons much as the molecules of a spherical drop of water contribute to the overall energy and surface tension.

In the collective model, high-energy states of the nucleus and certain magnetic and electric properties are explained by the motion of the nucleons outside the closed shells full energy levels combined with the motion of the paired nucleons in the core.

Roughly speaking, the nuclear core may be thought of as a liquid drop on whose surface circulates a stable tidal bulge directed toward the rotating unpaired nucleons outside the bulge. The tide of positively charged protons constitutes a current that in turn contributes to the magnetic properties of the nucleus. The increase in nuclear deformation that occurs with the increase in the number of unpaired nucleons accounts for the measured electric quadrupole momentwhich may be considered a measure of how much the distribution of electric charge in the nucleus departs from spherical symmetry.

Collective model. Info Print Cite. Submit Feedback. Thank you for your feedback. Collective model physics. See Article History. Alternative Titles: collectively deformed model, unified model. Read More on This Topic. For nuclei more removed from the doubly magic regions, the spherical-shell model encounters difficulty in explaining the large observed…. Learn More in these related Britannica articles:. For nuclei more removed from the doubly magic regions, the spherical-shell model encounters difficulty in explaining the large observed electric quadrupole moments indicating cigar-shaped nuclei.

For these nuclei a hybrid of liquid-drop and shell models, the collective model, has been proposed. See the…. Shell nuclear modeldescription of nuclei of atoms by analogy with the Bohr atomic model of electron energy levels. It was developed independently in the late s by the American physicist Maria Goeppert Mayer and the German physicist J.

Hans D. Jensen, who shared the Nobel Prize for Physics in….

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Nonlinear Oscillations in Mechanical Systems. Observations of Gas in the Infrared Spectrum.In physicsmotion is the change in the position of an object over time. Motion is mathematically described in terms of displacementdistancevelocityaccelerationspeedand time.

The motion of a body is observed by attaching a frame of reference to an observer and measuring the change in position of the body relative to that frame. If the position of an object is not changing relatively to a given frame of reference, the object is said to be at restmotionlessimmobilestationaryor to have a constant or time-invariant position with reference to its surroundings.

As there is no absolute frame of reference, absolute motion cannot be determined. Motion applies to various physical systems: to objects, bodies, matter particles, matter fields, radiation, radiation fields, radiation particles, curvature and space-time. One can also speak of motion of images, shapes and boundaries.

So, the term motion, in general, signifies a continuous change in the positions or configuration of a physical system in space. For example, one can talk about motion of a wave or about motion of a quantum particle, where the configuration consists of probabilities of occupying specific positions.

The main quantity that measures the motion of a body is momentum. An object's momentum increases with the object's mass and with its velocity. The total momentum of all objects in an isolated system one not affected by external forces does not change with time, as described by the law of conservation of momentum.

An object's motion, and thus its momentum, cannot change unless a force acts on the object. In physics, motion of massive bodies is described through two related sets of laws of mechanics. Motions of all large-scale and familiar objects in the universe such as carsprojectilesplanetscellsand humans are described by classical mechanicswhereas the motion of very small atomic and sub-atomic objects is described by quantum mechanics.

Historically, Newton and Euler formulated three laws of classical mechanics:. If the resultant force F acting on a body or an object is not equals to zero, the body will have an acceleration a which is in the same direction as the resultant. Classical mechanics is used for describing the motion of macroscopic objects, from projectiles to parts of machineryas well as astronomical objectssuch as spacecraftplanetsstarsand galaxies. It produces very accurate results within these domains, and is one of the oldest and largest in scienceengineeringand technology.

Classical mechanics is fundamentally based on Newton's laws of motion. These laws describe the relationship between the forces acting on a body and the motion of that body. Newton's three laws are:. Newton's three laws of motion were the first to accurately provide a mathematical model for understanding orbiting bodies in outer space. This explanation unified the motion of celestial bodies and motion of objects on earth. When an object moves with a constant speed at a particular direction at regular intervals of time it's known as the uniform motion.

For example: a bike moving in a straight line with a constant speed. Modern kinematics developed with study of electromagnetism and refers all velocities v to their ratio to speed of light c.

Accelerationthe change of velocity, then changes rapidity according to Lorentz transformations. This part of mechanics is special relativity. Efforts to incorporate gravity into relativistic mechanics were made by W.

Clifford and Albert Einstein. The development used differential geometry to describe a curved universe with gravity; the study is called general relativity. Quantum mechanics is a set of principles describing physical reality at the atomic level of matter molecules and atoms and the subatomic particles electronsprotonsneutronsand even smaller elementary particles such as quarks. These descriptions include the simultaneous wave-like and particle-like behavior of both matter and radiation energy as described in the wave—particle duality.

In classical mechanics, accurate measurements and predictions of the state of objects can be calculated, such as location and velocity. In the quantum mechanics, due to the Heisenberg uncertainty principlethe complete state of a subatomic particle, such as its location and velocity, cannot be simultaneously determined.

In addition to describing the motion of atomic level phenomena, quantum mechanics is useful in understanding some large-scale phenomenon such as superfluiditysuperconductivityand biological systemsincluding the function of smell receptors and the structures of protein. Third law of the Newtonian motion states that "For every action, there is an equal but opposite reaction".

Humans, like all known things in the universe, are in constant motion;  : 8—9 however, aside from obvious movements of the various external body parts and locomotionhumans are in motion in a variety of ways which are more difficult to perceive.