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.
Homework Statement
A billiard ball ( mass = 10kg, initial velocity is 5 m/s) is launched along x-axis at a stationary billiard ball ( mass = 5kg). After collision, the first ball goes off at 30 degree angle above x-axis and 2nd ball goes off at 45 degree angle below x-axis. Calculate the...
Homework Statement
http://postimage.org/image/j2ccrtjp1/
Here is a scan of my work. The problem is on the scan. Just trying to derive the velocity of the target in an elastic collision, as sketched in the image...
Can't seem to find the problem for the life of me.
1. An object of unit mass moving with unit speed applies unit force to any object when the two collide. True or False?
How can this definition shown to be equivalent to the definition F=ma of Newton. Here its different because we are considering how much a body applies a force not how much...
Homework Statement
Determine whether velocity is conserved in elastic and inelastic collisions? Use your experimental data to support your results.
Homework Equations
I have my data charts which show that velocity is not conserved in inelastic collisions, but in elastic collisions some...
Homework Statement
A proton strikes a stationary alpha particle (4He nucleus) head-on. Assuming the collision is completely elastic, what fraction of the proton’s kinetic energy is transferred to the alpha particle?
Homework Equations
Pi = Pf
Ki = Kf
The Attempt at a Solution
For...
if a hard sticky mud ball is trown on a wall it sticks to it
it is an inelastic collision
K.E. is not conserved
but here momentum is also not conserved because mud had an initial velocity
so initial momentum of mud + initial momentum of wall (that is 0) = initial momentum of mud
final...
Homework Statement
A mosquito flies toward you with a velocity of 2.2 km/h (E). If you are traveling toward the mosquito with a speed of 1.9 m/s, and a distance of 21.0 m separates you and the mosquito initially:
A) What will your displacement be when you hit the mosquito? (7)
B) How long...
Hello Physics Forums!
Homework Statement
The student sets up a collision experiment with two masses on a horizontal air track, with two springs on each end. The mass of A is 100 g and B is 200 g. Each spring has a constant of 20 N/m. Spring 1 (left side) was initially compressed 5 cm [left] to...
When Gamma Rays collide it is possible to form various units of matter (ie proton, electron, etc). Does anything happen when photons collide that are of other frequencies other then a ricochet? If X-Rays collide with other x-rays does anything happen? Also, if anything does happen, what would...
A car of mass 1200kg traveling at a velocity of 15m/s North collides head on with a small van of mass 2200kg traveling at 10m/s South. The vehicles stick together on impact and the collisions can be considered an isolated one. The contact time of the collision is 0.4 seconds.
Calc the...
My understanding, please correct me if I am wrong, is that in the LHC proton-to-proton collision experiments it is technically not feasible to align protons directly into each other. Why is that and where can I look this up?
Hello again everyone!
I've been plowing through yet another worksheet and thought I'd been okay until my solutions and formulas stopped working :( I was wondering if someone could tell me what I'm doing wrong. Thanks for reading!
Homework Statement
- A 225g ball moves right with a...
Someone told me I'd be more likely to get help here. Say you have these two balls moving in opposite directions. The balls float in the air and thus by themselves have negligible friction, but each is carrying a (detachable) bar across the ground, which has friction. On the very instant the...
Say you have these two balls moving in opposite directions. The balls float in the air and thus by themselves have negligible friction, but each is carrying a (detachable) bar across the ground, which has friction. On the very instant the balls collide with each other, they let go of their...
Looking at some old code I wrote for a game.
It has objects that collide, and rebound from each other. Where two collide, or one collided with a boundary, I knew how to work out the new trajectories and speeds.
In the case of multiple body collisions I had no clue. I broke them down randomly...
Just a question. I'm just getting back into re-learning my physics, and learning physics I never had a chance to study.
But...Do you know?... If two atoms - with velocities - collide and recoil, how much energy is lost from their velocities/momentum?
Is there a formula?...Does it have...
so they take the total energy of thos decays particles like quarks and add them to see how much energy they have, eventyally after millions of collisions they would find out if there was a higgs particle there?
is this kind of correct?
Homework Statement
The thermal conductivity of Cu at room temperature is 400 W/(mK). Use this value to determine the average time between collisions, \tau. Compare this value with the electrical conductivity.Homework Equations
Not sure. I take T=300K for room temperature.
From a book and with...
A thought experiment: X is a particle moving horizontally 0.8c to right, L is a light beam moving vertically to up, and O is an observer at rest. With precise timing in test arrangement, light beam hits X directly from below and gets absorbed by X (all beam's energy transfers to kinetic energy...
Homework Statement
See the attachment for the diagram. 'A' is a fixed point at a height 'H' above a smooth horizontal plane. An ideal string of length 'L' (>H) has one end attached to 'A' and the other to a particle. The particle is held horizontally (the string is taut) and released. The...
Hi everyone!
I recently read a problem in a university textbook that read about an inelastic collision. There are two pucks (hockey?) on the ice, one at rest. Both the same mass, one approaches the other at a velocity and when they collide they stick together and both move off with a velocity...
When considering the case of two or more point masses colliding in a 2 dimensional plane, is there any way to determine the final state completely from the initial conditions? if not is it not a blow to the deterministic ways of classical physics...
Homework Statement
2 protons collide at centre of mass energy of 7 TeV and produces a higgs with mass 100GeV and 2 protons:
pp -> ppH
calculate maximum energy of both protons in the final state
The Attempt at a Solution
Assuming higgs is produced at rest in lab frame (so...
Homework Statement
I solved this problem simply by substituting the initial and final velocities in vector form and applying the principle of conservation of momentum, but there's something I don't understand about this problem.
"Two small smooth spheres A and B have equal radii. The mass...
Conservation of Mechanical Energy and Momentum in total inelastic collisions?
In an inelastic collision, such as a bullet getting stuck in a block hanging on a string, has two types of conservations?
-Total Inelastic Collisision Conservations:
(1) Conservation of Mechanical Energy: Uo+Po =...
hi there,
I have been working on this particular problem for some weeks?months? now, and it has me quite stumped. I need to calculate the x,y,z co-ords of a golf ball after it has been putted into a hole, when it contacts the opposite rim, assuming it is traveling fast enough to contact the...
Heat or deformation cannot contribute to velocity here, as per the view of conservation on momentum. So how is it that momentum is conserved but kinetic energy is not given a perfectly inelastic collision?
The two masses stick together.
There is no intrinsic means of expressing lost due to...
I was curious, why is energy conserved in elastic collision but not in perfectly inelastic collision? It said this in my textbook without giving any reason why.
In an oblique collision (when one object hits another object of IDENTICAL mass at a slight angle the two objects move at right angles to each other.
my book says
p2 = p12 + p22
For momenum conservtation:
p= p1+ p2
apparently these equations can only be consistent of the collision occurs at...
A smooth spherical particle with mass 2.5 kg collides with a second smooth spherical
particle of mass 6kg. Before the collision, the first particle has velocity 9ms^1
in the positive x-direction while the second particle has velocity 6ms^1 in the positive y-direction. At the instant of...
Homework Statement
For a lab, I have performed a completely inelastic collision using 2 masses. One mass is 0.583 kg, and the other is the unknown we have to find. Using an air table, I was given the dots to show the movements of the objects as they intersect and them move together. I have...
Predicting Collisions of 2 objects (EDITED)
Homework Statement
Object 1 is at the origin. Object 2 is currently at 10 meters east and 20 meters north(10, 20) moving directly north at 30m/s . If Object 1 is moving at 70m/s, at what angle would Object 1 have to travel in order to collide with...
Hi,
I am trying find equations for continuous "stretchy" collisions, in other words, I have two perfectly round objects of known mass, radius, and velocity, and want to collide them and be able to have them squish together and then bounce apart. I am aware of the method of solving for the...
A light passenger vehicle weighing 1470 N collides with a train engine weighing 1.23 x 105
N, which was being moved from one rail siding to another. The train engine and the vehicle were entangled after the accident and from your measurements you have been able to determine they skidded 15 m...
Homework Statement
I am working on a simulated lab in which we have a single particle projectile launched at a target particle (located at the center of the circular chamber) of similar weight. Once the collision takes place, I record the time it takes for the scattered projectile to travel...
Homework Statement
When deriving the Ideal Gas Formula from the Kinetic Theory of Gases, we assumed that the gas molecules made perfectly elastic collisions with the walls of the container. This assumption is not necessary as long as the walls are at the same temperature as the gas. Why?
The...
Homework Statement
In a simple cubic lattice of spacing 0.2nm a phonon traveling in the {1 0 0} direction with wavelength 0.42nm collides with another phonon of the same wavelength which is traveling in the {1 1 0} direction. Draw a reciprocal space diagram to show the magnitude and...
http://desmond.imageshack.us/Himg843/scaled.php?server=843&filename=23518417.jpg&res=medium
The crucial thing I'm not understanding here is how they know that after the collision (shown at the bottom of the picture), the horizontal velocities of each particle are reversed. Surely we don't...
My understanding of relativity is that if two masses are in constant motion relative to each other, either one of them could be considered at rest with the other moving and it makes no difference which. However thinking about a collision between a big truck and a small car makes me wonder about...
I just got a doubt regarding object collisions and could not find any relevant information on web. I suppose to put on my question here for help.
when the two objects that are independent or dependent together are colliding each other, an other third object want to pass through these objects...
Since particles are really better described as exponentially decreasing energy amplitudes fields in a configuration space (space-time)...how close do the max energy point of a particle and the max energy point of a antiparticle have to be before they annihilate? This critical distance between...
I've just found out that in the centre of mass frame, the angle of deflection in a collision is different from in the lab frame.
I vaguely understand why: if the frame you viewed the particles in was also moving but only horizontally it would make their horizontal movement appear to decrease...
Good day all.
First of all, I apologize if this has been asked a million times before. I have not been able to find a straight-forward answer to my wonderings; maybe because they do not yield a straight-forward question.
As part of a large exercise of thinking for the joy of thinking*, I am...
Homework Statement
A 2.0 kg block slides along a frictionless surface at 1.0 m/s. A second block, sliding at a faster 4.0 m/s, collides with the first from behind and sticks to it. The final velocity of the combined blocks is 2.0 m/s. What is the mass of the second block?
Homework...
Is it to possible to use the special case of elastic collisions in one dimension with bodies that posses different mass. Ordinarily I know that if the body has same mass the velocity of the bodies will simply be exchanged but is the fact also hold for body with different masses?
v_1 - v_2 =...
Lets say that I have a cart on a track with silly putty on the end. This first cart is moving with an initial "x" velocity. There is another cart about a foot ahead of it with sillyputty on its bumper also. (Both carts have the same mass) This cart has an initial velocity of zero. Of course...
Homework Statement
A moderate force will break an egg. However, an egg dropped on the road or sidewalk usually breaks, while one dropped on the grass usually does not break. This difference is because for the egg dropped on the grass:
A. the change in momentum is greater
B. the change in...