What is Collisions: Definition and 706 Discussions
In physics, a collision is any event in which two or more bodies exert forces on each other in a relatively short time. Although the most common use of the word collision refers to incidents in which two or more objects collide with great force, the scientific use of the term implies nothing about the magnitude of the force.
Some examples of physical interactions that scientists would consider collisions are the following:
When an insect lands on a plant's leaf, its legs are said to collide with the leaf.
When a cat strides across a lawn, each contact that its paws make with the ground is considered a collision, as well as each brush of its fur against a blade of grass.
When a boxer throws a punch, their fist is said to collide with the opponent's body.
When an astronomical object merges with a black hole, they are considered to collide.Some colloquial uses of the word collision are the following:
A traffic collision involves at least one automobile.
A mid-air collision occurs between airplanes.
A ship collision accurately involves at least two moving maritime vessels hitting each other; the related term, allision, describes when a moving ship strikes a stationary object (often, but not always, another ship).
In physics, collisions can be classified by the change in the total kinetic energy of the system before and after the collision:
If most or all of the total kinetic energy is lost (dissipated as heat, sound, etc. or absorbed by the objects themselves), the collision is said to be inelastic; such collisions involve objects coming to a full stop. An example of such a collision is a car crash, as cars crumple inward when crashing, rather than bouncing off of each other. This is by design, for the safety of the occupants and bystanders should a crash occur - the frame of the car absorbs the energy of the crash instead.
If most of the kinetic energy is conserved (i.e. the objects continue moving afterwards), the collision is said to be elastic. An example of this is a baseball bat hitting a baseball - the kinetic energy of the bat is transferred to the ball, greatly increasing the ball's velocity. The sound of the bat hitting the ball represents the loss of energy.
And if all of the total kinetic energy is conserved (i.e. no energy is released as sound, heat, etc.), the collision is said to be perfectly elastic. Such a system is an idealization and cannot occur in reality, due to the second law of thermodynamics.
Hi, I am trying to decide on a topic for my senior project, and my professor and I fleetingly discussed my idea of writing a program that models collisions of macroscopic objects using the mutual repulsive forces of their valence electrons rather than standard conservation laws. My question is...
Homework Statement
A 1.0-kg particle is moving in the +x direction at 4.0m/s when it collides elastically with a 4.0-kg particle moving in the −x direction at 1.0m/s After colliding the 1-kg particle moves off at 130 counterclockwise from the positive x-axis. Find the final speeds of both...
Homework Statement
http://i.imgur.com/c5pOIe8.png & http://i.imgur.com/zdxfXLE.png
Sitting in a parking lot you witness a minor, but still noteworthy collision between two cars. You wondered, "Is momentum really conserved in collisions?" It didn't seem like it was in the real world so...
Is it possible to have a zero vector? The question arises in the context of conservation of momentum. In center of mass reference frame, the momentum of two masses involved in an elastic collision is zero before (as well as after) collision. It is because the two masses have equal and oppposite...
A surprising find looking for something else:
http://www.physics.usyd.edu.au/~cross/
Somewhat extensive notes on various small-ball sports physics - including material on collision physics and a neat vid of a falling slinky.
I've mined:
Ball bounce for comparative data for experiments...
I'm curious to know what tends to be 'left over' after particle collisions at sites like LHC. I realize that many different particles may arise, depending on the types of particles used for collision, as well as the kinetic energy put into the experiments. Despite the amazing diversity of...
Please clear up this problem...
Mass 1 = 8 kg, and v = 3 m/s to the right.
Mass 2 = 4 kg, and v = -3 m/s to the left.
Both objects are on the same x-plane. Totally elastic collision.
Momentum of mass 1 is 24, and momentum of mass 2 is -12.
How do I determine final momentum for each...
Homework Statement
A 25g object moving to the right at 20cm/s overtakes and collides elastically with a 10g object moving in the same direction at 15 cm/s. Find the velocity of each object after the collision
Homework Equations
Ʃp=Ʃp'
v1+v1'=v2+v2'
The Attempt at a Solution
First...
As far as I understand: In the Drude model we take the electron to be moving in a random direction after each collision (*), such that the mean velocity is simply the average of -eEt/m, which is just -eEτ/m, where τ is the relaxation time.
But I am very confused about this basic assumption...
1. This was a hard test question that I took partial credit on. I want to fully understand what I did wrong so that I’m fluid with the concept. I’m also new to this forum. I love constructive criticism too! lol
Zombie Apocalypse has arrived and the war has begun. Your task as a physics student...
Homework Statement
a ball of mass 2.50kg is thrown upward. it leaves the hand w/ an upward velocity of 19.6m/s.
(on the way down now )after the ball hits the throwers hand it comes to rest in .20s
a. What is the impulse exerted on the ball?
b. What is the average net force on the ball...
Now although this is silly and quite crude (You have been warned), it is a legitimate physics question. I was sitting on the toilet a few days ago and I got some splash back. I started thinking about elastic collisions and how no matter what, nothing is perfectly elastic (correct?). Why would...
Homework Statement
If there are two asteroids A and B of equal mass (and density of 3000kg/m^3), with the same semi major axis of a=2.2 AU with asteroid A having a circular orbit and no inclination, and asteroid B has an elliptical orbit with an eccentricity of e=0.05 and an inclination of...
I remember seeing a demo of collisions inside a conductor. It was a long board with nails representing the atom positions (a square lattice arrangement) and you would put a hand full of marbles at the top. The marbles will slide down but since they keep hitting the nails the velocity will be...
Hi,
I tried to solve this problem myself and I'd like someone to check it :) Thanks already!
A ball is rolling towards a block, which is connected to a spring. Assume no friction occurs. The initial velocity of the ball is 10 m/s. The spring constant is k = 5 N/m. Mass of the ball = 5 kg and...
Consider a unit volume (rigid walled container of surface area S) containing N molecules with diameter d, having a maxwellian speed distribution with a mean time between collisions t*.
Allowing for a stable (i.e constant) equilibrium mono-layer distribution of some number of these molecules...
I am unsure how to proceed with this problem because it is asking for the final velocity of one of the two objects given the initial velocities. This is an inelastic collision not a completely inelastic collision, which means the two objects do not stick together. The book makes a distinction...
When doing practice problems from my textbook, I often get confused with both of them.
MOre specifically there are usually formulas which pertain to only one of those types of collisions.
Ex: (v_1-v_2)_i = -(v_1-v_2)_f
Does anyone know more of these types of formulas, or tricks to...
Homework Statement
Two Smooth spheres of masses m and 3m move with speeds u and v in opposite directions. The smaller mass is brought to rest.
(i) show that the coefficient of restitution,e, is given by e =(u - 3v)/(3u + 3v)
(ii) show that u ≥ 3v
Homework Equations
m1u1 + m2u2 =...
Homework Statement
A smooth sphere falls vertically and strikes a fixed smooth plane inclined at an angle of ∅ to the horizontal.If the coefficient of restitution is (2/3) and the sphere rebounds horizontally,
Its speed before impact is u and after impact v
calculate the fraction of kinetic...
So this question I have is so obvious that it's probably not even worth talking about from a scientific point of view but I just can't keep it out of my head. The moderators are welcome to delete this if they think it's too silly.
Suppose there is a person tied to the windshield of a car. When...
Question: If one creates a wormhole (theoretically has a space/hyper drive) and one is going from point A to point B, and there is a moon or planet in the way, intersecting the path...
What might happen? Is a wormhole out of space/time of this dimension and thus the craft would pass through...
Homework Statement
A 50g object is moving east at 0.3 m/s. A 100g object is moving east as well at 0.25 m/s. These objects have an inelastic collision.
a) Find their final velocity
b) Find the kinetic energy lostHomework Equations
P1 + P2 = P3 + P4 ; momentum is conserved
Ek = 1/2 mv^2The...
Homework Statement
(a) Show that E2 - p2c2 is a Lorentz invariant, where E is the total energy, p is the momentum, c is speed of light.
(b) In the lab frame, an utlra-relativistic electron with γ = 100 collides head-on with a photon of energy E. Find the threshold energy E required to...
Trying to understand what happens upon impact to the metal of a car that is stopped (Vehicle 1)when another car's driver's side rear (Vehicle 2) impacts the stationary car . Vehicle 2 is a heavier, larger car and is moving in reverse at approximately 10-15 MPH. The impact site on Vehicle 1 is...
Homework Statement
A ball A is dropped from rest from a
height of 2.0 m above the floor. Meanwhile that ball A is released, an other ball B is pushed away with the starting speed v_0 from the position shown in Figure. Which angle α is needed for B to collide with ball A?
Homework...
Question:
In the following link I'm concerned with only pages 1 and 2. I'm wondering if there is a typo or an error of some kind. I feel like there is some inconsistency to what the author refers to as \upsilon, \theta, and \phi. The only angle shown in the diagram is \upsilon, which is the...
When we use Boyle's Law it means that as pressure increases the volume of the container would decrease. In my notes they stated that if I were to halve the volume there would be two times the number of collisions per second which implies that the force exerted is doubled. But why is this so? I...
Could someone please check my answers so far for this question as its getting very messy so I'm not sure if I've made a mistake :/
Two particles of masses 2m and m are moving along the x−axis with constant velocities u1i and u2i respectively...
Suppose that a mass M1 is moving with speed V1 and collides with mass M2 which is initially at rest. After the elastic collision they make, both momentum and kinetic energy are conserved.
m_{1}v_{1f} + m_{2}v_{2f} = m_{1}v_{1i}
\frac{1}{2}m_{1}||v_{1i}||^{2}=...
Homework Statement
In a game of billiards the 0.165 kg cue ball is hit toward the 0.155 kg eight ball which is stationary. The cue ball travels at a speed of 6.2 m/s and after impact rolls away at an angle of 40.0 degrees counterclockwise from its initial direction with a velocity of 3.7 m/s...
Ok - this is a moderately tough question which I can't figure out.
So I am trying to work on a simplified model to start with.
I imagine a solid, very massive impenetrable object.
I have a tube or any long object which can exhibit some elastic behavior and also plastic behavior...
Homework Statement
I'm currently doing a coursework project for physics on oblique collisions. I have done two different experiments, both with preliminaries etc.. The first experiment involved suspending a hockey ball (henceforth known as the striking ball) on a bifilar pendulum and releasing...
1.So the problem given is the following, "A small wooden block with mass 0.775 kg is suspended from the lower end of a light cord that is 1.58m long. The block is initially at rest. A bullet with mass 0.0134 kg is fired at the block with a horizontal velocity v0. The bullet strikes the block...
Homework Statement
Ground-state hydrogen atom with 12 ev kinetic energy collides head-on with another ground-state hydrogen atom at rest. Using principles of conservation of energy and momentum, show that an inelastic collision cannot occur. Therefore the collision must be elastic...
Homework Statement
Hi!
I have found an interesting statement. It says, that if we have a system of two masses and a wall (all collisions will be elastic ones) with one mass (lets label it as 1) trapped between the other mass (2) and the wall and if there is no friction, then if ratio of...
Vehicle A (1400-kg) traveling 60˚ north of east collides with Vehicle B (1000-kg) traveling North. After the collision Vehicle A is moving at 12.13 m/s at 35˚ from its original path. Vehicle B is moving at 10.85 m/s at 10˚ from its original path. Find the initial velocities of both vehicles...
Hello,
I am stuck on the last page of my physics post lab. The lab was on elastic, super elastic and inelastic collisions. The point of the lab is to see whether or not momentum and kinetic energy is conserved during each scenario.
I'm pretty sure that in the elastic and super elastic...
So the way we learned to solve elastic collisions is to use the center of mass reference frame. I calculated that the COM is moving at v=1.66 m/s relative to the lab frame. Next I calculated the velocity of the white ball to be +1.66 m/s relative to the COM frame and the black ball to have...
Homework Statement
A 0.30 kg puck A, initially at rest on a frictionless horizontal surface, is struck by a 0.20 kg puck B
that is initially moving along the x-axis with a velocity of 2.0 m/s. After the collision, the 0.20
kg puck has a speed of 1.0 m/s at an angle of θ = 530 to the positive...
Homework Statement
Molecules in an ideal gas collide with each other at random times. The probability distribution governing the time between collisions is P(t) = Ae^(-bt).
(a) Find the value of A so that P(t) is correctly normalized.
(b) Find the average time between collisions, t. This...
Is it ever the case in particle accelerators such as the LHC that a collision occurs involving three or more particles (e.g. two particles collide then some of the debris from that collision impacts a third particle)?
Does the same phenomenon.also occur in cosmic ray collisions (I would...
Can the products of high-energy particle collisions include the creation of electromagnetic/strong/weak/gravitational fields (whether transient or not) in parallel with or in lieu of other new particles?
IH
I'm finding it difficult to understand how momentum is conserved in an inelastic collision, but kinetic energy isn't. I understand some energy leaves the system in the form of sound and heat.
If we look at the momentum of the system before and after the collision, P=mV, they are equal, due to...
Homework Statement
A 2.0 kg ball moving with a speed of 3.0 m/s hits, elastically, an identical stationary ball. If the first ball moves away with an angle 30 degrees to the original path, determine the speed of the first ball after the collision, and the speed and direction of the second...
Homework Statement
A truck (4 000 kg) runs a red light and enters an intersection traveling at 81 km/h [E]. The truck collides with a car (2
000 kg) that was traveling at 54 km/h [N20oW]. Immediately after the collision the truck was traveling at 60 km/h [N
30o E]. Determine the velocity...
Hey, I'm not sure if this should be in the chemistry or physics section,. Hopefully it is in the right place. I have a question about molecular collisions: specifically, what actually happens when two molecules "collide". Perhaps a better question is: "what constitutes a molecular collision?"...
A 25000 kg truck moving at 40 m/s on a road angled at 17° hits a 10000 kg van moving at 25 m/s on a road angled at 60° at an intersection between two the two roads. Since this is a two-dimensional perfectly inelastic collision, what is the final velocity of the wreck?
Not sure about which...
The title says it all. I'm contrasting "stable matter" with short-lived particles that quickly decay into something else. (The E=mc2 equation implies that it's possible, but in terms of stable matter, I'm familiar only with it being destroyed, say, in nuclear explosions.) Are ordinary...