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
Block A of mass, mA = 2.0 kg, is moving on a frictionless surface with a velocity of 5.0 m/s to the right and another block B of mass, mB = 8.0 kg, is moving with a velocity of 3.0 m/s to the left, as shown in the diagram below. The two block eventually collide.
d. If...
Homework Statement
A 0.321 kg puck, initially at rest on a horizon-
tal, frictionless surface, is struck by a 0.227 kg
puck moving initially along the x-axis with
a speed of 2.51 m/s. After the collision, the
0.227 kg puck has a speed of 1.51 m/s at an
angle of 31 degrees to the...
Hey these could be simple questions with easy formulas and just plugging in but i don't have them my teacher is the worst teacher i have ever had in high school and what help i can get is appreciatedHomework Statement
A 68.0 kg ice skater moving to the right with a velocity of 2.99 m/s throws a...
Moonbear, I've just found another possible research project for you using your sheep!
http://arxiv.org/abs/0711.3804
You can verify the physics of what these people have calculated by letting your sheep head-butt and determine if there's any brain damage! :)
Don't you just love it when...
Homework Statement
Particle 1 has initial velocity v, directed to the right, and particle 2 is initially stationary.
Let the mass of particle 1 be m and the mass of particle 2 be 3m. If the collision is perfectly inelastic, what are the velocities of the two particles after the collision...
Homework Statement
A ballistic pendulum is a device used to measure the velocity of a projectile. The projectile is shot horizontally into and becomes embedded in the bob of a pendulum as illustrated below. The pendulum swings upward to some height h, which is measured. The mass of the bullet...
Homework Statement
A car with mass of 950 kg and speed of 16 m/s approches an intersection in the positive x direction. A 1300-kg minivan traveling at 21m/s is heading towards the same intersection in the positive y direction. The car and minivan collide and stick together. Fine the speed and...
Homework Statement
Marble A, mass 5g moves at a speed of 20 cm/s. It collides with a second marble B, mass 10 g, moving at 10 cm/s in the same direction. After the collision, marble A continues with a speed of 8 cm/s in the same direction. A) Calculate the momentum of each marble before the...
Homework Statement
A block of mass M is resting on a horizontal, frictionless table and is attached as shown above to a relaxed spring of spring constant k. A second block of mass 2 M and initial speed v0 collides with and sticks to the first block.
Develop expressions for the following...
Homework Statement
A particle of relative mass 4 travels at velocity v, and collides with a stationary particle with relative mass 1. By considering the zero momentum frame, show that the larger particle can be deflected by an angle of arcsin(1/4) at the most.
(Note this is a...
Collisions between atomic and subatomic particles are usually perfectly elastic. In one such collision, a proton traveling to the right at 274 km/s collides elastically with a stationary alpha particle (a helium nucleus, having mass 6.65×10−27 kg . I am trying to figure out the velocity of after...
Homework Statement
What is an example of an elastic equation on earth?
Homework Equations
N/A
The Attempt at a Solution
Is a ball bouncing on the ground a good example of an elastic collision? (If it is)
In outer space a rock with mass 4 kg, and velocity < 3900, -3000, 3200 > m/s, struck a rock with mass 17 kg and velocity < 300, -260, 260 > m/s. After the collision, the 4 kg rock's velocity is < 3500, -2300, 3700 > m/s.
What is the final velocity of the 17 kg rock?
m1 = 4 kg
v1 = < 3900...
Two balls, of masses mA = 40 g and mB = 72 g are suspended as shown in Figure 7-44. The lighter ball is pulled away to a 60° angle with the vertical and released.
(a) What is the velocity of the lighter ball before impact? (Take the right to be positive.)
(b) What is the...
A 1.0 kg magnetized air puck moving across a level table at 0.24 m/s approaches head-on a stationary, similarly magnetized air puck of mass 0.50 kg. If the "magnetic collision" is repulsive and perfectly elastic, determine:
(a) the velocity of each puck after the collision
(b) the velocity of...
Homework Statement
A bullet with a mass of 4.0 g and a speed of 653 m/s is fired at a block of wood with a mass of 0.093 kg. The block rests on a frictionless surface, and is thin enough that the bullet passes completely through it. Immediately after the bullet exits the block, the speed of...
I'm doing a lab were we used photogates to calculate the time before and after the collision.
I have an initial Photogate Time and a Final Photogate Time..
Working in excel I need to caculate the velocity final and initial using those times. I also need to find KEi KEf Pi and Pf.
I've...
There are the 3 spheres in a line, of masses m , m and M. The 2 spheres on the right are slightly separated and initially at rest, the left sphere is incident with speed Vo. Assuming head on elastic collisions:
a) if M =< m , show that there are two collisions and find all the final...
Homework Statement
A block of mass m1=1.88 kg slides along a frictionless table with a speed of 10.3 m/s. Directly in front of it, and moving in the same direction, is a block m2=4.92 kg moving at 3.27 m/s. A massless spring with a force constant k=1120N/m is attached to the backside of m2...
A 5.00 kg Ball A moving at 12.0 m/s collides with a stationary 4.00 kg Ball B. After
the collision, Ball A moves off at an angle of 38.0º right of its original direction. Ball B 52.0º left of Ball A's original direction. After the collision, what is the momentum
of Ball A?
P1 + P2 = P1'...
Homework Statement
Hi,
My question probably has a simple answer, but I've been scratching my
head over it a little too long so I thought I would ask it here. I
have three initial photons involved in a collision with 4-momenta k1,
k2 and k3. I have two reference frames:
frame 1: the...
Hi,
My question probably has a simple answer, but I've been scratching my
head over it a little too long so I thought I would ask it here. I
have three initial photons involved in a collision with 4-momenta k1,
k2 and k3. I have two reference frames:
frame 1: the centre of mass frame of...
ive been researching cosmic rays, and came across this question that i can't quite work out. can anyone help?
what is a cosmic ray proton of Etot 10^9 Gev, collides head on with a low energy photon from remnant 3K balck body radiation in the universe.
if the photon has energy kT, can we work...
hi, just wondering if someone could help me with some questions about collisions in accelerators. i have a 1TeV proton beam being collided with a) a fixed target, b) a 50GeV electron and c) an antiproton beam. i have to find the max available energy for the production of new particles in each...
Hello,
I have recently been interested in the problem of 2- and 3-dimensional elastic collisions. I just don't understand how to solve these problems analytically: in the 2D case we have 4 variables (x,y components of the velocity times 2 bodies) and only 3 equations (2 conservation of...
Homework Statement
Beginning Calculations in Physical Chemistry
Barry R. Johnson & Stephen K. Scott
Calculate the average number of collisions per second between N_{2} and O_{2} molecules in air @ 298K and @ a pressure of 1 X 10^5 in a room of volume V = 100m^3. (Assume air has the...
Friends:
I understand that collisions at high speeds cause a lot more damage. Like when micro meteors strike satellites. Can someone explain how this physics differs from normal collisions? At what velocity do these effects become enlarged? I read about an electromagnetic gun whose...
Hi, I'm trying to figure out the number of g's something undergoes after being dropped and hitting the floor. So far I've figured out that I need the time it takes for the collision to occur. I know it's not instantaneous, but I can't find any information on it, so can you point me in the right...
Putty of mass 5 is compresses a spring with stiffness consonant 3. The spring is stretched and the putty has a completely inelastic collision with another putty of mass 15. How fast and how far do the putties travel?
I have no idea how to begin.
thanks,,
Hi everyone, i was just wondering, when two objects of the same mass collide (in an elastic collision) the angles that they bounce off from should combine to 90 degrees. right? so I'm trying to prove this, but I'm a little stuck. i used vector component equations, but i arrived at a little...
Homework Statement
Given a particle of mass m in box of length L, how would you find the frequency of collisions on a given wall and the momentum of each collisions?
Homework Equations
The Attempt at a Solution
Should I start with the equation for the root-mean-square-velocity...
Hi,
Was doing a bit of work the other day and I was looking at collisions. Thinking about real collisions compared to ideal ones and the thing in particular which stands out is that often when two vehicles (for example) collide the striking vehicle will continue to travel some distance in its...
i recently read that it was possible to acelerate an electron, using a synchrotron to 3/4 c !
Does this imply that if two electrn beams were to be accelerated in this way that the resultant velocity of a collision would be 3/2 c ?
If so what would this b like, i.e. there be lots of mass...
Homework Statement
Which of the following statements are true about elastic and inelastic collisions?
True False for elastic collisions, linear momentum is conserved but kinetic energy is not
True False for inelastic collisions, neither linear momentum nor kinetic energy is conserved...
Hi there :biggrin:
I'm having a bit of a conceptual difficulty regarding the equations for inelastic collisions. Suppose a body of mass M1, moving at initial velocity V1, collides and sticks to another body, mass M2, moving at some other initial velocity V2. They then move together with a...
Homework Statement
A uniform symmetric ellipsoid (Mass M) has a large semi axis c and small semi axis a. A particle of mass m<<M is moving along a straight line parallel to the x-axis. Its y-coordinate is a/2 and its z-coordinate it c/2. After an inelastic collision, it sticks to the ellipsoid...
Homework Statement
A bullet of mass m moving with velocity V_o crashes into a block of mass M at rest on a frictionless horizontal surface the block is sitting at the edge of a table that is H high. When the bullet hits the block it flies off the table and it lands a distance x from the bottom...
This is a homework question from my thermal physics class. (Problem 6.40 from Schroeder's Introduction to Thermal Physics).
Homework Statement
"You might wonder why all the molecules in a gas in thermal equilibrium don;t have exactly the same speed. After all, when two molecules collide...
Say we have two waves of the same amplitude are about to collide with each other.
The preceeding wave travels at a slightly higher speed before interacting with the final wave. However, instead of passing through the final wave its speed and size is transferred into the final wave where it...
hi, i am doing a lab about analyzing one-dimensional collisions.
There are two synthesis questions that i don't know how to even begin with.
1. How could the results of this investigation be applied to determine the mass of a sealed refuse bag on board the International Space Station...
Hi,
I'm wondering if I'm forgetting some key point about elastic collisions from my basic mechanics. If you don't want to read my lengthy solution, just read the problem statement and then answer the following: can this problem be solved essentially at a glance, without the lengthy algebra I...
According to a textbook that I was looking at, electron capture and electron-proton collisions both produced a neutron and an antineutrino, but one was mediated by a W+ particle and the other by a W-. Is this correct, or are they interchangeable?
Homework Statement
1) Two identical bodies, each with rest mass m(o), approach each other with equal velocities u, collide and stick together in a perfectly inelastic collision. Determine the rest mass of the composite body.
Homework Equations
The Attempt at a Solution
The...
Homework Statement
In 1986, four high school students built an electric car that could reach a speed of 106 km/h. The mass of the car was just 60.0 kg. Imagine two of these cars performing in a stunt show. One car travels east with a speed of 106.0 km/h and the other travels west with a...
Can QFT be used to anything else but particle collisions? Particle collisions seem to be the major application of the theory, but it hasn't become clear to me if it works for anything else.
I need help with this question please:
A 25.0g object moving to the right at 20.0cm/s overtakes and collides elastically with a 10.0g object moving in the same direction at 15.0cm/s. Find the velocity of each object after the collision.
The answer is: 17.1cm/s (25.0g obect), 22.1cm/s...