Tagged Questions

Interaction between two or more bodies that results in physical contact and an exchange of momentum between the bodies involved.

381 views

Is there difference in force when the height increases?

Consider a man with mass 50kg. When he jumps from a 2 meter height, the total force is $F=ma$ ie (mass * gravity), but nothing happens to him. When he jumps from a 50 meter height, the total force ...
I was asked to compute the average force exerted by a rigid spherical ball (mass $m$) on the floor over time $t \rightarrow \infty$, in a situation where the ball is dropped vertically from a height $... 1answer 213 views Relativistic Kill Vehicle What would happen if a significantly supra-molecular object (say ranking from grams to low kilotons) would be accelerated to relativistic speeds (>.10 c) such that its worldline would intersect with a ... 2answers 67 views Does inelastic collision say the ball bounces back to you when thrown at an angle on ground? I created a bounce simulation using exactly the formula from Wikipedia. The behavior I observe is not what I would expect in two cases: When two balls hit off-centre, they act the same as if the ... 2answers 186 views What exactly will happen if a small planet collides with earth This is a video of a simulation of Ceres (a dwarf planet) hitting Earth at 2000km/s. What strikes me the most, is how fast the shockwave is moving. It takes about 6 minutes for the shockwave to pass ... 1answer 43 views Can the speed of a vehicle be determined based upon the extent of injuries to a pedestrian? While driving at night in a Prius, at varying speeds of 5-20 MPH in heavy, stop-and-go traffic on a 4 lane city street, two pedestrians in dark clothing were struck (not in a crosswalk). One died of ... 1answer 120 views Collisions of celestial objects When massive, spherical celestial objects collide, how long does it take for the objects to coalesce into a new, larger, spherical entity under the influence of gravity? Examples of the above:- ... 3answers 738 views Why are ions and electrons at different temperatures in a plasma? In plasmas, the collision rate among ions or electrons is much larger than the collision rate between ions and electrons. Why is that so? 1answer 566 views Simple 2D Vehicle collision physics I'm trying to create a simplified GTA 2 clone to learn. I'm onto vehicle collisions physics. The basic idea I would say is, To apply force F determined by vehicle A's position and velocity onto point ... 0answers 294 views Modelling an Inelastic Collision I've attempted to model the inelastic collision between a moving mass and a large stationary object, e.g. dropping an ball on the floor, for analysing the approximate kinematics and heat dissipation ... 1answer 108 views Is change in kinetic energy invariant? Consider the inelastic collision between two bodies. This question follows on from this: Is the coefficient of restitution frame independent and energy conservation?. One of the answers to this ... 1answer 75 views Relationship of multiple particles under collision [closed] Consider 3 particles. All 3 particles travel along the x-axis. The 1st particle possesses some mass, m, and its initial position is somewhere on the negative x-axis. It has some (positive) velocity ... 2answers 2k views What is the relative speed of two near-light speed particles headed towards each other? I understand that nothing can move faster than light due to time dilation. I want to build upon my understanding of Einstein's theory of Special Relativity, so I came up with this hypothetical problem ... 2answers 5k views Inelastic collision and conservation of linear and angular momentum Is it possible for two spheres (a & b) to have an inelastic collision with BOTH the total linear and angular momentum preserved? I'm doing some physics simulation of some spheres attracting each ... 3answers 627 views The theory of moon creation when a Mars size planet hit Earth As we know the predominant theory where does the moon come from is that a Mars size planet hit the earth and took a chunk out of it which eventually materialized into moon. My question is that if a ... 4answers 591 views In an elastic collision, can we choose between cons. of energy and cons. of momentum? Suppose we have two solid spheres with masses$m$and$M$, respectively, and that$m$is significantly less than$M$. The lighter sphere is placed directly on top of the heavier one, and the two are ... 3answers 3k views Conservation of 4-momentum in special relativity I understand that the inner product of two 4-vectors is conserved under the Lorentz transformations, so that the absolute value of the four momentum is the same in any reference frame. This is what I (... 2answers 133 views Explicit Function for Bouncing Ball [closed] I was wondering if it's possible (and if so, how would you go about it) to write an explicit function for the position of a ball bouncing as a function of time (assuming a coefficient of restitution 0 ... 2answers 292 views Reflection - reaction force direction Let's say an object hits a wall. When the object is reflected does the direction of the reaction force caused on the wall look like the red arrow? Does that direction depend on how "strong" object is ... 3answers 2k views Simple elastic collision If a particle with mass$m$collides with a wall at right angles, and the collision is perfectly elastic. The particle hits the wall at$v\ ms^{-1}$. There is no friction or gravity. So the particle ... 3answers 1k views What are the general solutions to a hard sphere collision? [duplicate] Surely someone has found the solutions to the hard sphere collisions (in$n$dimensions) of two bodies of mass$m_1$and$m_2$, respectively--that is the resultant velocities (or momenta) of the two ... 3answers 26k views Small car colliding with large truck A small car collides with a large truck. Why do both vehicles experience the same magnitude of force? Wouldn't the large vehicle experience less force than the small one? 1answer 573 views How to get the new direction of 2 disks colliding? I'm developing a 2D game including collisions between many disks. I would like to know how I can get the angle corresponding to the new direction of each disk. For every disk I have this information :... 3answers 874 views Train crash: are these situations alike? [duplicate] I was just wondering... I believe that if a car travelling 50 miles per hour crashes into a wall, the result should be the same as crashing to another car also travelling 50 miles per hour (but in the ... 3answers 223 views What is the strange event in this simulation of a galactic collision? I was watching this video on YouTube: 2 Spiral Galaxies w/Supermassive Black Holes Collide Around half way, and again almost at the end, the black holes seem to suddenly give off some sort of force ... 2answers 888 views Why can't collisions be elastic? I understand that in inelastic collisions thermal energy is given out, but why does that happen? Why can't they simply rebound without giving off energy? Also, why in some collisions more heat is ... 2answers 180 views Is the reaction force for a stone hitting a wall infinite? Let us assume a rigid stone which moves in empty space with a constant speed of$v$. (Or in the air with no friction and drag or you can imagine a free fall with friction). This stone hits a rigid ... 1answer 611 views Can solids behave like liquids? Basically, the more I look at things the more it seems like there's entirely no difference between a liquid and gas, it all just depends on the relative density of what's around it. This being said, ... 2answers 57 views Ideal energy to study higgsstrahlung at a lepton collider Referring to this diagram: I understand that any energy excess could be taken away as kinetic energy of the final$h$and$Z$. If you are interested in this (kind of) process should you tune the ... 2answers 136 views Cosmology: collisionless vs collisional fluids? I try to understand the difference between collisionless and collisional fluids in cosmology. My first question is the following. In the context of FLRW cosmology, we suppose that the Universe can ... 2answers 1k views Factors on which Coefficient of restitution depend What are the factors on which coefficient of restitution depend? What is the reason for more coefficient of restitution of two glass balls (0.95) than for two lead balls (0.20)? 1answer 108 views A question regarding collisions Let us consider a system of 2 identical spherical bodies connected by a massless string that is taut. If one body is placed at the origin then the other is placed at some coordinate$(x,y)$. The ... 2answers 872 views What causes damage, kinetic energy or momentum? Let's assume we have 2 bullets. The first bullet has$450J$of KE and$3kg.m/s$of momentum, while the second bullet has$250J$of KE and$5kg.m/s$. Now if they are both shot at ballistic ... 2answers 2k views Heat generated by collision Suppose there are two objects: A = m1 and B = m2 . A is travelling at a constant velocity v toward B and collides inelastically: is there a way in which I could determine the energy which is ... 1answer 102 views Collision of light waves & matter When light or electromagnetic wave hits an obstacle, what happens? Are the reactions times always negligible? By reaction I mean all that happens after the hit like reflection for example. 1answer 153 views What would happen if two entangled particles collided? Does that is even possible? I have almost zero knowledge in quantum physics, it is just a curiosity that popped in my mind. 3answers 411 views What's the outcome of two polarized electrons beam collide head on? Let's say that I have two electron beams targeted towards each other along x-axis. Both beams are polarized on axis (z-axis) perpendicular to x-axis. Another beam's polarization is up and another down ... 2answers 556 views How to calculate velocities after collision? I'm currently writing a program for a particle simulator. One of the requirements is that the particles collide in a realistic way. However, I don't know how to calculate the final velocities. For ... 2answers 227 views How is the Principle of Conservation of Momentum proven using the Momentum-Impulse Principle? Consider two particles moving in the same direction on the same line,$A$and$B$, with mass$m_A$and$m_B$, respectively. They also have velocies$u_A$and$u_B$. They collide. After the collision A ... 1answer 98 views Finding the coffecient of restitution A ball moving with velocity$1 \hat i \ ms^{-1}$and collides with a friction less wall, afetr collision the velocity of ball becomes$1/2 \hat j \ ms^{-1}$. Find the coefficient of restitution ... 1answer 643 views Kinetic energy loss when a rigid body falls into water Assume you have a rigid body falling into the ocean at terminal velocity. Also assume that the rigid body does not break on impact. How could you figure out how much kinetic energy would be lost in ... 1answer 48 views Collision/Crumpling problem possible solution mistake This question is from Physics for scientist and engineers , Ohanian . Two automobiles of 540 and 1400 kg collide head-on while moving at 80 kmh in opposite directions. After the collision the ... 2answers 96 views Newton's Cradle: why does it stay symmetric? [duplicate] How is it that always the same number of balls leave at the other end in Newton's cradle. I understand that the momentum needs to be conserved, but as momentum is defined as p=m*v couldn't you have a ... 2answers 28 views Motion after a collision of objects not involved in it [closed] I'm confused about collisions where there are parts of the objects not involved in it. How do these parts move after the collision? I'll make an example. Consider a cart with an incline attached (... 1answer 234 views Why does the rule that elastic collisions are at 90 degrees in 2 dimensions not apply? When one object collides with another object of the same mass in a 2D plane, we know that we can derive that the angles that the objects leave the collision at add up to 90 degrees in a perfectly ... 1answer 49 views Alpha Particles Moving Object I'd like to apologize in advance because this may be a silly/obvious question, but could alpha particles theoretically move an object? My basic idea is that alpha particles could cause an object to ... 2answers 526 views Elastic collisions and conservation of momentum If you have an elastic collision between objects 1 and 2 and where 'kinetic energy is conserved', does this mean object 1 will always have the same velocity it had before the collision? Or will ... 1answer 267 views Finding direction of a ball after collision in cartesian coordinate system [closed] In elastic collision of ball to wall along x axis m*Vix=m*Vfx as velocity of wall is 0 before and after collision thus Vix=Vfx ......eq(1) Kinetic Energy is conserved so m*Vi2 = m*Vf2 (Vix2 + Viy2)=... 1answer 57 views Is this process possible for L=0?$e^+e^- \to 2\eta_c\$
For the following $$e^+ e^- \to \eta_c \eta_c$$ I think it violates parity conservation so it can't happen, but is there any other reason as to why it can't take place? Or is it actually possible?