What is Collision: Definition and 1000 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 particle P is projected from the origin with initial speed 5 m/s and projection angle theta. At time t = 0, when P is at the origin, another particle Q begins to move on the
(horizontal) x-axis with initial speed 15/4 m/s and constant acceleration a = 3g/4 m/s^2...
Homework Statement
Two uniform bars have masses and lengths of m, l and 2m, 2l, respectively. The bars are pivoted at the common frictionless hinge as shown. The bars are released from the horizontal position in such a way that they collide and stick together at the bottom position. After...
Homework Statement
Two identical masses collide. one is at rest. what are their final velocities.
Homework Equations
The relative velocities before and after the collision are identical:
##v_1-v_2=-(u_1-u_2)##
The Attempt at a Solution
I draw the final velocities in the same...
One ball has a mass of m1 = 0.250 kg and an initial velocity of 5.00 m/s. The other has a mass of m2=0.800 kg and is initially at rest. No external forces act on the balls. What are the velocities of the balls after the collision? Elastic Collision.
On the book I have this formula.
STEP 1#...
In an elastic collision against a wall, where the angle of incidence is equal to the angle of deflection, why is it assumed that friction effected no impulse, and only the normal force did? I can understand if this was stated in the problem by saying "frictionless surface, or whatever" but this...
Definition/Summary
A collision is said to be inelastic if the total kinetic energy of all the bodies involved in the collision changes.
So conservation of kinetic energy does not apply.
But conservation of momentum, and of angular momentum, does apply to all unrestrained collisions...
Definition/Summary
A collision is said to be elastic if the total kinetic energy of all the bodies involved in the collision remains constant.
Most collisions are NOT elastic.
Conservation of momentum applies to ALL unrestrained collisions.
Equations
For a two body collision...
Homework Statement
Ball 1, with a mass of 110g and traveling at 15m/s , collides head on with ball 2, which has a mass of 350g and is initially at rest.
What are the final velocities of each ball if the collision is perfectly elastic?
Homework Equations
Conservation of momentum:
m1u1 +...
say that a particle collides elastically with a wall 60 degrees from the wall's normal. the force from the wall is along the wall's normal. My questions is why there is no parallel component to the force from the wall since the particles velocity had a parallel component.
So I know how to solve for two initially moving objects that collide one way, but I was reading on this website another way to do it and I am not understanding a step. I've included a picture of the site and underlined the step I don't understand. I've tried a couple ways but I can't get it...
This problem comes from the inelastic collision section.
Homework Statement
"In Fig. 9-63, block 1 (mass 2.0 kg) is moving rightward at 10 m/s and block 2 (mass 5.0 kg) is moving rightward at 3.0 m/s. The surface is frictionless, and a spring with a spring constant of 1120 N/m is fixed to...
Homework Statement
Hello. I was solving this problem about two balls in a plane colliding elastically. The first one had mass 100g radius 5cm and started with velocity of 3m/s to the right and hit the second ball with mass 50g radius 3cm(initially stationary). It hit the second ball such...
Homework Statement
We have a sphere of mass M=0.75 Kg hung from the ceiling by a massless tense cord. Said sphere is hit by a projectile/bullet of mass m=0.015 Kg with velocity v_{0}=300 m/s and they are stuck together (inelastic collision). Find the height the (projectile+sphere) object...
Here is the problem :
Two heavenly bodies (m1 and m2) (non orbiting) in free space at a distance D are released from rest and allowed to approach each other under gravitational influence to a final distance d.
This is the way I've worked the problem :
The total potential energy difference...
Hi, everyone! This is my first post on this website. I answered the first part of the problem correctly, but I have gotten Part B wrong many times (after trying different approaches) and haven't attempted Part C yet. I would really appreciate any and all advice and assistance with this problem...
Hello! I need help with this physics problem, I've some what attempted it and I need some feedback. ANY help would be awesome!
Homework Statement
Two objects (A and B) of equal mass, undergo an elastic collision in deep space. Initially, B is at rest and A approaches at velocity v. The...
Homework Statement
Two identical shuffleboard disks, one orange and the other yellow, are involved in a perfectly elastic glancing collision. The yellow disk is initially at rest and is struck by the orange disk moving with a speed of 4 m/s. After the collision, the orange disk moves along a...
Homework Statement
A ball of mass = 3-kg moving to the right at 3 m/s collides elastically with a ball of mass m2 = 2 kg moving at 4 m/s to the left. Find (a) the final speed of each object and (b)
the kinetic energy of each ball before and after the collisions.
Homework Equations
V1i...
Homework Statement
Homework Equations
∑F=ma
The Attempt at a Solution
This is a problem that can be solved by looking at impulse and momentum and I understand how the problem is solved in the book but I'm wondering about the reasoning before, if this is the only way to look at it...
Homework Statement
A 90-kg halfback running north with a speed of 9 m/s is tackled by a 120-kg opponent running south with a speed of 3 m/s. If the collision is perfectly inelastic and head-on, calculate. (a) the velocity of the players just after the tackle and (b) the total energy lost as a...
Homework Statement
The cross section of ##^{59}Co## for capturing the thermal neutrons is ##2000 fm^2##. A ##10g##, thin paper of ##^{59}Co## is radiated for ##100 hours## in reactor with neutron flux ##2\cdot 10^{18} /m^2s##. Density of ##^{59}Co## is ##8.9g/cm^3##. Half life time of...
Homework Statement
2 masses moving on a friction less surface. one of 2 kg moving at a speed of 10 and one of 6 kg moving at the speed of 4. at the back of the heavier one is a spring with a constant k=800.
What is the maximum shortening of the spring
Homework Equations
Conservation of...
The ball (mass m) strikes the heavy steel plate (mass M) with a velocity of v=30m/s at an angle of 60 degrees with the horizontal. the plate is initially stationary. If the coefficient of restitution is e=0.7 and the spring stiffness is k=155N/m. Calculate the final velocity of the ball and the...
Homework Statement
I made an example, two masses colliding elastically according to the drawing. i only know the direction of the first mass after collision (can i determine also the velocity?)
I try to solve but i go into difficulties.
Homework Equations
Conservation of momentum...
Homework Statement
In a one dimensional elastic collision there are two equations: conservation of momentum and conservation of energy. by solving those 2 sets we get that the relative velocity before equals minus the relative velocity after:
v_1-v_2=-(u_1-u_2)
Is this equation valid also in...
Homework Statement
A body of mass 3 kg slides on a friction less surface with velocity 4 m/s and collides elastically with a resting mass of 2 kg. calculate the final velocities.
Homework Equations
Conservation of momentum: m_1v_1+m_2v_2=m_1u_1+m_2u_2
Conservation of energy...
What will happen if we collide two neutrons?
As far as I know,since they have no charge, there won't be any repulsive forces. So one neutron will go through the other.:eek:
Is this true? What about nuclear fission? Why does the neutron split the nucleus when there are no forces present?
Sorry if this question has already been considered in this Forum (I'm sure it is but I can't find it now).
A rigid ball slide without friction in an horizontal plane and collide elastically with a wall, the plane of which is perpendicular to the ball's velocity.
During the collision the ball...
Homework Statement
The problem is what are the odds of an incident object of radius r1 colliding with any of a collection of target objects of radius r2, where the r2 objects have a number density N / m^3 = n and the incident object travels a distance L. Incident object is moving much faster...
Homework Statement
A 50 gram steel ball moving on a frictionless horizontal surface at 2.0m.s^-1 hits a stationary 20 gram ceramic ball. After the collision the ceramic ball moves off at a velocity of 2.5m.s^-1.
(i) Calculate the velocity of the steel ball after the collision.
(ii) Calculate...
This may be intuitively obvious to you and I'm just missing it.
Say you had 3 balls each with a mass of 1g. Each moving at velocity of 10m/s on a 2D Cartesian plane. Ball 1 & 2 are moving toward the origin from opposite sides, so they are approaching each other at 20m/s. Ball 3 moving from...
Homework Statement
After a completely inelastic collision, two particles of the same mass m and same initial speed v are found to move away together with the speed (2/3)v. Find the angle between the initial velocity vectors of the objects.
The Attempt at a Solution
It is completely...
Homework Statement
A 2 kg mass with initial velocity v = (5i + 7j) collides perfectly elastically with a 3 kg
mass with initial velocity v = (-1i -3j) After the collision, the 2kg mass has a speed of
√50 m/s and the 3 kg mass is traveling at an angle of 329.77Θ as measured from the...
Homework Statement
What is the minimum proton energy needed in an accelerator to produce antiprotons by the
reaction:
P+P \rightarrow P+P+P+\bar{P}
The mass of both protons and antiprotons is m_p. Assume first that the initial protons have equal
energy (the lab frame is the...
Homework Statement
https://scontent-a-sjc.xx.fbcdn.net/hphotos-prn1/t1.0-9/603671_1409914319284787_3441607163537875560_n.jpg
Homework Equations
conservation of total momentum
M1V1+M2V2 = MtotVf
The Attempt at a Solution
I tried using the COTM
as such:
x...
when two sub atomic particles collide, being waves as well as particles. at point of collision do they act like radio waves and modulate each other. Are the resultant particle/waves produced by collision equivalent to upper and lower sidebands (as in AM modulation) or bessel functions (as in FM...
Homework Statement
A 1.0-kg block slides on a frictionless, horizontal air track with an initial velocity of v = 2.0 m/s. It collides with another 1.0-kg block, which is initially at rest. One end of an ideal massless spring of spring constant k = 200 N/m is attached to the second block, so...
Homework Statement
A block with large mass M slides with speed V0 on a frictionless table towards a wall. It collides elastically with a ball with small mass m, which is initially at rest at a distance L from the wall. The ball slides towards the wall, bounces elastically, and then proceeds to...
Homework Statement
I just did a lab on inelastic collisions and this was one of the discussion questions:
Consider a situation in which you are the driver of a car stopped at a red light and you see a car of similar mass approaching rapidly from behind. Use the results of your experiment...
Homework Statement
A 1343 kg car experiences an impulse of 30,000 N during a collision with a wall. If the collision takes 0.43 s, what was the velocity of the car just before the collision?
A) 22 m/s
B) 9 m/s
C) 51 m/s
D) 18 m/s
Homework Equations
F=dp/dt
p=mv
The Attempt at...
Homework Statement
A steel ball of mass m is fastened to a cord of length L and released when the cord is horizontal. At the bottom of the path, the ball strikes a hard plastic block of mass M = 4m at rest on a frictionless surface. The collision is elastic.
Find the speed of the block...
Ep = Ek
mgh = Ek
mgh = ½mv²
v = √2gh
As the collision is elastic, m1u1 + m2u2 = m1v1 + m2v2. It is known that m2 = 2m1.
m√2gh = 2m1v2
v2 = (m√2gh)/2m
v2 = (√2gh)/2
Force body diagram of m2:
̂̂̂̂̂̂Fnet = ma
Fnet = Fn + Fg + Ff
Fnet = Ff
m2a = Ff
a = Ff/m2
a = Ff/2m1
a =...
Homework Statement
In Fig. 9-64, block 2
(mass 1.0 kg) is at rest on a
frictionless surface and touch-
ing the end of an unstretched
spring of spring constant 200
N/m. The other end of the spring is fixed to a wall. Block 1 (mass 2.0 kg), traveling at speed v1 = 4.0 m/s, collides with...
Homework Statement
Simple question, if a dog jumps on a stationary sled at velocity v.. the dog weighs 20kg.
The velocity after is v/2. What is the weight of the sled
Homework Equations
m1v = (m1 + m2)v/2
The Attempt at a Solution
I rearrange this equation and i get m2 = m1.. this...
Homework Statement
Two small bodies initially at rest and free to move from a distance of 1m from each other are subjected to only their gravitational force of attraction. They approach each other and collide and do not separate. In respect to this collision which of the following statement is...
Homework Statement
A body of mass 2.0Kg makes an elastic collision with another body at rest and continues to move in the original direction but with one-fourth of its original speed. What is the mass of the other body?Homework Equations
Because it is an elastic collision I know that Energy and...
Homework Statement
A head on collision between mass and mass B occurs as described in the F vs s graph below.
Complete the table in the data section
Find \vec{x}A
Find \vec{x}B
see attached page for clarification
Homework Equations
P=m*v
\DeltaP=F*t
Ek=\stackrel{1}{2}mv2
\vec{d} = \vec{v}t...
Collision -- a ball and string form a pendulum...
1. A 1.0-kg ball is attached to the end of a 2.5-m string to form a pendulum. This pendulum is released from rest with the string horizontal. At the lowest point in its swing when it is moving horizontally, the ball collides elastically with a...
Impact and collision -- having problems
A smooth sphere A impinges obliquely with an identical smooth sphere B which is at rest. the direction of A before and after impact makes angles 60 and X , respectively, with the line of centres at impact. the coefficient of restitution is e.
prove that...
Hello,
My textbook says that if two equal masses, with the second one of them at rest initially, collide in an elastic collision. The first mass will stop and the second one will have the initial speed of the first mass.
WHY? This makes no sense to me. Elastic collision only means momentum...