# What is System of particles: Definition and 50 Discussions

A particle system is a technique in game physics, motion graphics, and computer graphics that uses many minute sprites, 3D models, or other graphic objects to simulate certain kinds of "fuzzy" phenomena, which are otherwise very hard to reproduce with conventional rendering techniques - usually highly chaotic systems, natural phenomena, or processes caused by chemical reactions.
Introduced in the 1982 film Star Trek II: The Wrath of Khan for the fictional "Genesis effect", other examples include replicating the phenomena of fire, explosions, smoke, moving water (such as a waterfall), sparks, falling leaves, rock falls, clouds, fog, snow, dust, meteor tails, stars and galaxies, or abstract visual effects like glowing trails, magic spells, etc. - these use particles that fade out quickly and are then re-emitted from the effect's source. Another technique can be used for things that contain many strands - such as fur, hair, and grass - involving rendering an entire particle's lifetime at once, which can then be drawn and manipulated as a single strand of the material in question.
Particle systems may be two-dimensional or three-dimensional.

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1. ### Center of mass acceleration for an inclined plane and mass m

Why is the center of mass acceleration zero? Did I do anything wrong?
2. ### System of particles, impulse and conservation of angular momentum

So i was able to solve the angular velocity part but i don't know how to find the velocity of centre of mass . For the first part i simply conserved momentum about COM because if i consider the particles as a part of the same system as rod the collision are internal forces . I am mainly...
3. ### B Conservation of Momentum for system of particles

We know that if we take two particles and assume no external force is applied then by Newtons third law total momentum gets conserved after collision. If we take three particles and there is collision between them and no external force then the momentum is again conserved for each pair like in...
4. ### I Statement about torque in a system of particles

Hello guys, I’m studying Newton’s Mechanics at the first year of engineering, and I would like to ask one question about torque. In my book I found this statement ‘’ Given a system of particles, it’s always possible to determine a pair of forces which torque is indipedent from the pole chosen...
5. ### Energy-momentum tensor for a relativistic system of particles

I think it is quite simple as an exercise, following the two relevant equations, but at the beginning I find myself stuck in going to identify the lagrangian for a relativistic system of non-interacting particles. For a free relativistic particle I know that lagrangian is...
6. ### Two rods, each with a free and a fixed ball and a spring

Since there are no external forces, the angular momentum (##L##) and linear momentum (##P##) are conserved. Let's call the left rod ##A## and the right one ##B##. If all the balls were fixed, I'd write ##L_0=L_f## ##L_A+L_B=(I_A+I_B)\omega_f## From this equation I can find the final angular...
7. E

### A single external force doing work on a system of particles

Suppose we have a system of particles being acted upon by a single external force ##\mathbf{F}^{e}##. Each individual particle feels a force of ##\mathbf{f}_i = \mathbf{f}_{i}^{int} + \mathbf{f}_{i}^{e}## such that ##\sum_i \mathbf{f}_{i}^{e} = \mathbf{F}^{e}##, and ##\mathbf{f}_{i}^{int}## are...
8. ### Several parts of a system and its CM

I have known and used this theorem for a long time solving problems ("Calculate the CM of the some given shape"). I took the theorem to be "obvious" and didn't know it could be proved (and that indeed it was a theorem at all). I can make no attempt at the proof. Any help would be welcome.

18. ### I Classical Field Theory for a system of particles

In classical field theory, the field, φ, is usually constructed from a very large number of coupled harmonic oscillators. Let's say our φ consists of just electrons. What does φ best represent physically, a very large number of electrons or can it represent just a few electrons? Which is the...
19. ### B Disentanglemt of a system of particles

Is it possible for an entangled system of particles to be disentangled at a distance, without making them interact directly with each other?
20. ### Moment of inertia of a collinear system of particles

Homework Statement Landau&Lifshitz Vol. Mechanics, p101 Q1 Find the moment of inertia of a collinear set of molecules Homework Equations I=sum m_i*(r_i^2) The Attempt at a Solution r_i= r_i'-r_cm where r_cm=sum m_i*r_i/sum m_i I=sum m_i r_i^2 I= 1/M sum m_i m_j (r_i' - r_cm)^2 I=1/M sum m_i...
21. ### How to check if frame is inertial?

inertial frame is one in which isolated particle has constant velocity but is there actually any "isolated particle " ? how then can frame be defined as or not being inertial ? or is it that - for a system in which acceleration due to external forces is equal for all members , the frame of...
22. ### Find the Lagrangian of a System of Particles

Homework Statement Ok, so in this system, there are two point particles of mass M connected by massless levers of length L. The pair of masses pivots about the upper point and rotates about the axis at an angular frequency ω. The lower mass is constrained to slide on the vertical axis. The...
23. ### Quantum State diagram for system of particles

Question: "Write the quantum state for the following system of particles distributed over evenly spaced energy levels" The diagram (couldn't upload so hope its not too rough): 5 ---------------------- 4 ---------------------- 3 --------------X------- 2 ------X---X------X---- 1...
24. ### Internal Forces in System of Particles

I am following along with Goldstien's Classical Mechanics Book and I am on page 11. The text is breaking down the total potential energy of a system into two parts: the external conservative forces and the internal conservative forces. My question pertains to the internal forces. Writing the...
25. ### Dynamics of a system of particles all influencing eachother

Take a closed system of particles. Each has it's own mass, but that's really about it for the sakes of this argument. Now suppose there is some standard force law that applies between particles, whatever it may be. (In general it will depend only on the separation between particles and thus be...
26. ### Define Force in a system of particles about point P

Homework Statement Define Force in a system of particles about point P Homework Equations The Attempt at a Solution I know force can be explained but not defined. However, i don't think you can just say the force is a push or a pull in a "system of particles about point P". Can...
27. ### How can a system of particles with kinetic energy have no momentum?

I thought objects with kinetic energy have to be moving... And moving objects have momentum... So how is it that something with kinetic energy can have no momentum? Could you give me specific examples of such cases? Thank you so much! :)
28. ### Center of Mass of system of particles

Homework Statement Four particles are in a 2-D plane with masses, x- and y- positions, and x- and y- velocities as given in the table below: M X Y Vx Vy 1 8.9kg -2.6m -4.8m 3.2m/s -3.9m/s 2 7.9kg -3.4m 3.6m...
29. ### System of particles passing over a pulley

1. Homework Statement Two particles of masses m1=8 kg and m2=5 kg are connected to the two ends of a light inextensible string which passes over a fixed smooth pulley. Initially each of the two particles are held at a position which is 5 m above a horizontal ground. The objects are then...
30. ### Torque direction for any system of particles

Homework Statement A particle is to move in an xy plane, clockwise around the origin as seen from the positive side of the z axis. In unit-vector notation, what torque acts on the particle at time t = 9.5 s if the magnitude of its angular momentum about the origin is (a) 8.0 kg·m2/s, (b)...
31. ### Newtons Second Law For A System Of Particles

Homework Statement In figure (a), a 5.4 kg dog stands on a 16 kg flatboat at distance D = 6.1 m from the shore. It walks 2.1 m along the boat toward shore and then stops. Assuming no friction between the boat and the water, find how far the dog is then from the shore. Homework...
32. ### Linear Momentum of A System of Particles

At time t = 0, a ball is struck at ground level and sent over level ground. The figure below gives the magnitude p of the ball's momentum versus time t during the flight. (p1 = 7.0 kg·m/s and the vertical axis is marked in increments of 0.5 kg·m/s.) At what initial angle above the horizontal is...
33. ### Centre of gravity of this system of particles

Homework Statement Find the centre of gravity of this system of particles Homework Equations attached image showing diagram http://www.zshare.net/image/7209360586277b98/ The Attempt at a Solution Taking moments about a, 4*0+6*30 = 184 then not sure Any help is greatly appreciated Thanks...
34. ### Internal forces on a system of particles

I am very much confused with this statements "The forces of action and reaction never cancels out each other , but the internal forces on a system of particles cancel out in pairs " I think i know the reason for the first statement.i.e,The forces of action and reaction are acting on different...
35. ### System of particles, linear momentum (easy problem)

Homework Statement A 2100 kg truck traveling north at 41 km/h turns east and accelerates to 51 km/h. (a) What is the change in the truck's kinetic energy? What are the (b) magnitude and (c) direction of the change in its momentum? Homework Equations currently using delta P = mvf - mvi...
36. ### Newton's Second Law for a System of Particles

Homework Statement A shell is shot with an initial velocity 0 of 29 m/s, at an angle of θ0 = 56° with the horizontal. At the top of the trajectory, the shell explodes into two fragments of equal mass. One fragment, whose speed immediately after the explosion is zero, falls vertically. How far...
37. ### Angular Momentum of a system of particles relative to another point

Homework Statement Two particles move in opposite directions along a straight line. Particle 1 of mass m1 = 23 kg at x1 = 16 m moves with a speed v1 = 34 m/s (to the right), while the particle 2 of mass m2 = 64 kg at x2 = −25 m moves with a speed v2 = −43 m/s (to the left). Given...
38. ### Motion of a system of particles

Homework Statement The vector position of a 3.15 g particle moving in the xy plane varies in time according to the following equation. r1 = (3i+3j)t + 2jt^2 At the same time, the vector position of a 5.00 g particle varies according to the following equation. r2= 3i-2it^2 -6jt For...
39. ### HELP System of particles problem

HELP!System of particles problem Homework Statement A 10kg dog walks 3m on a 20kg boat towards shore. How much nearer the shore does the dog end up if the boat was initially at rest. The Attempt at a Solution I am not really sure how to approach this problem. I think that the dog is 3...
40. ### Shell fragments exploding - NSL for system of particles

A shell is shot with initial velocity \vec{}v_{0} is 20ms^{-1} at an angle \vartheta = 60 degrees. At the top of the trajectory, the shell explodes into two fragments of equal mass. Fragment1 has a speed of 0 immediately after the explosion and falls vertically. How far from the gun does...
41. ### Potential Energy of a system of particles

A system consists of three particles, each of mass 4.00 g, located at the corners of an equilateral triangle with sides of 36.0 cm. (a) Calculate the potential energy of the system. m = .004, d = .2078 UG = Gm1m2/R U_total = sum of U_i U_total = Gm1m2/R + Gm1m3/R + Gm2m3/R U_total =...
42. ### Angular Momentum of a system of particles

Homework Statement Two particles move in opposite directions along a straight line. Prticle 1 of mass m1 = 26kg at x1 = 23 m moves with a speed v1 = 43 m/s(to the right), while the particle 2 of mass m2 = 63 kg at x2= -22 m moves with a speed of -37 m/s(to the left). Given: Counter...
43. ### Using Newton's Second Law for a System of Particles

The Problem: A 4 kg dog stands on a 16 kg flatboat at distance 12 m from the shore. The dog walks 5 m along the boat toward the shore and then stops. Assuming no friction between the boat and the water, find how far the dog is then from the shore. The dog's displacement is towards the shore...
44. ### Calculating Probability of Spin Measurement in System of Particles

Hey, I am a little confused with this system 1/2 particles spin at t=0 |PSI(0)> = 1/sqrt(3) (|+>_1|+>_2 + |+>_1|->_2 + |->_1|->_2 the values of S_1z and S_2z are measured at t=0. Then I have to calculate the probability that the same value will be found for the two particles. Any...
45. ### Momentum problem (motion of a system of particles?) Slingshot around moon

NASA often uses the gravity of a planet to slingshot a probe on its way to a more distant planet. The interaction of the planet and the spacecraft is a collision in which the objects do not touch. How can the probe have its speed increased in this manner? This problem confuses me, I want...
46. ### The Linear Momentum of a System of Particles

Hello All, I have a question that i can't seem to get. If someone could help me get started on part a that would be great. So far i have tryed using P =m1v1 and can't seem to find any other equations that would help with the problem. Any help is great! Thank You Problem: A cart...
47. ### System of particles - find energy

Iam having problems with this question i think my technique is right but i,ve made a mistake somewhere Particles of mass m and 2m respectively are connected by a light inextensible string. Initially, the particles lie at opposite edges of a smooth horizontal table with the string just taut...
48. ### The Explosion of a Vessel and Velocity of its Pieces

I need some help on how to solve this question, I don't really know how to do this at all. A vessel at rest explodes, breaking into three pieces. Two pieces having equal mass, fly off perpendicular to one another with the same speed of 30 m/s. The third piece has three times the mass of each...
49. ### Potential energy of a system of particles

Hi. In trying to convince myself that the total potential energy of a system of two particles was just the potential energy of one particle computed while considering the other particle fixed, I imagined two identical particles a distance 2r apart and attracting each other, and concluded that...
50. ### How to Find Particle Acceleration Using Conservation of Energy?

Help An isolated system of two identical particles, each of mass m, is described by an energy function E = ½ m |v1|^2 + ½ m |v2|^2 + ½ k |x1 – x2|^2 How can I use conservation of energy to find the acceleration of each particle in terms of the position of the particle? I would be thankful...