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.
Gas from another galaxy is hitting our own, triggering the birth of bright new stars and adding fresh luster to the Milky Way.
Link: Scientific American
I have 2 curves and I need to slide 1 of the circles along an axis until it exactly meets the other circle. How do I determine the distance until contact?
Homework Statement
A NASA satellite has just observed an asteroid that is on a collision course with the Earth. The asteroid has an estimated mass, based on its size, of 5 × 10^9 kg. It is approaching the Earth on a head-on course with a velocity of 595 m/s relative to the Earth and is now 5.0...
I have a quick question regarding causality in SR and some specific examples. Collision between two bodies is one of the examples when one event causes another, let's say that a body travels towards another which is at rest and hits it. Now my question may seem strange, but what is really the...
Homework Statement
Determine the fractional decrease in total kinetic energy of each set of asteroids when they collide. If the average specific heat of the material composing the asteroids is assumed to be that of ice (2.05 kJ/kg·˚C), by how much does the temperature of the asteroids rise...
Two masses m_1 and m_2 are closing each other with speeds v_1 and v_2 . The coefficient of restitution is e. Calculate the amount of kinetic energy loss after caused by the collision.
I solved it in the center of mass coordinates( v_{cm}=u_{cm}=0 ). The relative speed before and after the...
Hello. I'm a writer going back and doing some fact checking to make an important scene more believable. It involves a character, Lux in the backseat of a jeep which has just suffered a head on collision with a bus. But I think I am doing something wrong because the numbers I get don't seem to...
Homework Statement
Consider a photon colliding with an electron and scattered directly backward. If the electron is initially at rest and the incident photon has frequency f, determine the frequency of the back-scattered photon
Homework Equations
The Attempt at a Solution
Since the...
1. A steel ball of mass 0.400 kg is fastened to a cord 60.0 cm long and fixed at the far end, and is released when the cord is horizontal. At the bottom of its path, the ball strikes a 2.00 kg steel block initially at rest on a frictionless surface. The collision is elastic.
Assuming the...
N2 + 3H2 -----> 2NH3,
For this reaction to occur does one nitrogen have to collide with 3 hydrogen molecules, or should 3 nitrogen molecules collide with 3 hydrogen molecules to break up the bonds? I just brought up this example because of it's stoichiometry not for any other reason. Thanks in...
Hi,
I am wondering if total momentum of the system is conserved in this case. Our system is consisted of two balls: one is falling vertically down to ground, another is thrown vertically up, so they collide in air. Is total momentum of the two balls conserved after the collision?
Now I...
Homework Statement
You are just starting a new job as investigator for the car collision investigation. You assist your superior in order to determine, as accurately as possible, the circumstances surrounding collisions (initial velocity of the vehicles involved, direction vehicles were...
Football Player 1 (mass m1 = 72 kg) has just caught a pass at the 50 yard line when he is tackled by Football Player 2 (of mass m2). Each player was initially moving at an angle of theta with respect to the 50 yard line at 8.0m/s. the tackle is a perfectly inelastic collision and the players...
Homework Statement
A 0.50 kg ball with a speed of 1.5 m/s in the positive direction has a head-on elastic collision with a stationary 0.80 kg ball. What are the velocities of the balls after the collision?
Homework Equations
I've used the Ek = (1/2)m(v^2) so far.
The Attempt at a...
Homework Statement
A homogenous, thin stick with the mass m and the length l is hanging from the ceiling and can rotate freely around the point P.
A small ball with the mass of M is attached to the end of the stick.
The small ball on the end of the stick gets hit by another small ball with...
Homework Statement
A particle with speed v1 = 2.64 × 10^6 m/s makes a glancing elastic collision with another particle that is at rest. Both particles have the same mass. After the collision, the struck particle moves off at 45º to v1. The speed of the struck particle after the collision is...
Homework Statement
A ball is attached to one end of a rod. A second ball hits the ball with velocity u. The collision is inelastic and both balls after the collision travel together with a new velocity v.
The rod is attached to the ceiling at a point with no friction. The moment of inertia...
Homework Statement
Hi, could someone help me with some physics homework for a head on collision between a truck and a car. Truck and car are going the same speed (50mph) but truck weighs 5 times more than car.
Q.1. What is the force on each car?
Q.2. What is the impulse?
Q.3. Explain in...
We have 2 masses: one with mass \(M\) with velocity \(V_0\) and the other with mass \(m\) and velocity \(0\).
\begin{align}
MV_0 &= MV_0' + mv'\\
M(V_0 - V_0') &= mv'\qquad (*)\\
MV_0^2 &= MV_0^{'2} + mv^{'2}\\
M(V_0 - V_0')(V_0 + V_0') &= mv^{'2}\qquad (**)
\end{align}
So let's take...
What is the physics explanation of why, when you play pool, and one ball slams into another ball, does the ball originally in motion become stationary and the other ball takes on all the velocity?
Homework Statement
1200kg car moving at 9.72m/s runs into and sticks to a parked 1000kg car. The collision takes 0.15s and after the crash the cars wheels lock and they skid to a stop on u=0.40 road. What is the impact force on both cars?
Homework Equations
J=F*t=m*dv
The Attempt at a...
Homework Statement
A stick of mass m and length l is pivoted at one end. It is held horizontal
and then released. It swings down, and when it is vertical the free end elastically collides.
Assume that the ball is initially held at rest and then released a split second before the
stick strikes...
In kinetic theory a liquid is viewed as an incompressible substance in which the atoms are free to move. I would like to know how to find an expression for the molecular flux in a liquid. By molecular flux I mean the collisions per unit area, where collision refers not to the collision between...
Homework Statement
Consider a bar of length L, mass M, and uniform density floating in free space (ie: neglect gravity and assume that it is not contacting anything). The bar is initially stationary. Imagine a bullet of mass m traveling at a speed v hits the bar at one end. What is the...
I was wondering what happens when sub-atomic particles collide together. Could the energy created from this event cause other sub-atomic particles to be drawn in? If so would there be a second explosion from too much mass collecting in one small space?
Homework Statement
A uniform square plate of mass m and side a can freely rotate about a vertical axis passing through one edge. It is initially at rest. A particle of mass m is moving horizontally and perpendicular to the plane of the plate with velocity u. The particle collides with the...
Homework Statement
In deep space a 7.0 kg rubber ball moving along the x-axis with a speed of 20 m/s collides ELASTICALLY with another ball of mass = 25 kg. After the collision the 7.0kg rubber ball's velocity is directed in the positive y axis. Find the final speed of the 7 kg ball, as well...
I have a 3DOF gryo with massless bearings and gimbals that is enclosed in case or cylinder. The cylinder will limit the range of motion of the gyro. Please see the pictures.
I am trying calculate rotor velocities in pitch and yaw after a collision with the cylinder wall. The...
physics question?? proton/antiproton collision find velocity
Homework Statement
A proton and antiproton collide with equal and opposite momentum at the SPS collider in Geneva to form a single massive particle which is 10 times more massive than a proton. What is the velocity (as a fraction of...
Hi all,
I am trying to understand about collision frequency that happened in ionosphere layer. In D region, below 90 km [Wait and Spies 1964] the ionospheric electron-neutral collision frequency given as
v(h) = 1.816x10e11 exp(-0.15h)
I just wondering, to who ever really expert in...
I have a question; If two particles (let's say protons) collide at high speed, they can produce heavy particles, like the Higgs. My understanding is that the high velocities make the particles more massive, allowing them to produce higher mass particles (relativity).
So... If I fly past...
My class was given a packet with several scenario questions. I've got the rest of them completed and this is the only one remaining.
So I know that the question involves: Momentum Conservation (2-D): Inelastic collisions, Work-energy: Conservation of energy with friction, Dynamics: Newton's...
Suvat equations -- car braking hard to avoid a collision
Homework Statement
A car (A) is speeding along a rural road, of width 4m with a speed of 25m/s when the driver sees another vehicle (B) of length 3.5m just starting to cross the road at a point 40m ahead. The drivers reaction time is...
Homework Statement
You throw a baseball at a 45 degrees angle to the horizontal, aiming at a friend who's sitting in a tree a distance, h, above ground. At the instant you throw your ball, your friend drops another ball.
a) Show that the two balls will collide, no matter what your ball's...
In an inelastic collision of a moving billiard ball with a second ball at rest, I understand that the two balls have the same velocity after contact, correct?
But at the instant of contact how do the velocites of the two balls change instantaneously? Doesn’t that imply an infinite force...
Homework Statement
A person driving a car suddenly sees a wall .At that instant velocity of the car is v. Coefficient of static and kinetic friction is μ. The mass of the car is M. To avoid the driver should ...(acc. due to gravity=g)
a)apply breaks
b)turn (the car shouldn't slip while...
The problem is like this
Assume both cars A and B are intially traveling to the right at 98 ft/s. Car A is tailgating leaving very little room between car A and car B. At that instant driver of car B notices a n accident and starts to break witha deceleration of 2o ft/s^2. By the time the...
Homework Statement
The problem concerns the collision of a particle on a rigid, fixed disk of radius R. The coefficient of friction is zero, and the coefficient of restitution is 0 < ε < 1, such that vperpendicular, final = εvperpendicular, initial .
A) Show that tanαincident = εtanαfinal...
Homework Statement
A solid wood door 1.00 m wide and 2.00 m high is hinged along one side and has a total mass of 49.0 kg. Initially open and at rest, the door is struck at its center by a handful of sticky mud of mass 0.500 kg, traveling perpendicular to the door at 15.0 m/s just before...
Hello,
I have difficulties with this problem:
The body mass m1 = 20 g is fired with a spring, k = 72 N / m from position A. On arrival at point B hits completely elastic body mass m2 = 15 g.
Find the distance x of compressed spring so that the mass m2 reaches point C separated a distance d...
From University Physics,
Homework Statement
Canadian nuclear reactors use heavy water moderators in which elastic collisions occur between the neutrons and deuterons* of mass 2.0 u (see Example 8.11 in Section 8.4).
(a) What is the speed of a neutron, expressed as a...
Hi,
Homework Statement
I'd like to find the minimum mass M which will render possible a second collision between M and the two masses m and the spring in the attachment, and also the time between the two collisions. It is stated that the initial velocity of M is v0 as indicated and that the...
Homework Statement
An electron with KE 5eV is incident on a H atom in its ground state. The collision
A)must be elastic
b)may be partially elastic
c)must be completely inelastic
d)may be completely inelastic
More than one option may be correct
Homework Equations
The Attempt at a...
Homework Statement
Suppose that two elastic balls moving through three dimensional space collide and rebound, conserving both kinetic energy and momentum. The balls cast shadows, and these shadows moving over a flat two-dimensional surface come together, collide and rebound. Now pretend the...
1. Hi,
I'm a computer engineering graduate. I'm developing a computer game similar to Soundrop (Apple). The situation is: balls fall vertically down under the effect of gravity. There are various inclined planes in the frame (of known angle of inclination). There could be multiple...
Homework Statement
Suppose that an earth-mas object collides with a neutron star with radius 10 km and mass 1.4 $M_{sun}$. The material of the earth-like object would wrap around the neutron star and form a thin layer on top of the original neutron star surface. Assume the material gets...
1. A neutron collides elastically with a helium nucleus (at rest initially) whose mass is four times that of the neutron. The helium nucleus is observed to rebound at an angle '2 = 41° from the neutron's initial direction. The neutron's initial speed is 5.6 105 m/s.
Determine the angle at...
Homework Statement
A car is driving and hits the brakes for l1 distance before colliding with another car at rest who has the brakes on. After the collision they slide distance l2 together while braking.
The mass of both cars are known, and the friction between the road and the wheels is known...
Homework Statement
A halfback with a mass m1=90kg is running up field with a speed of v1=7.6m/s. He is tackled by an opponent with a mass of m2=120kg, who approaches the halfback at an angle of 30 degrees with a velocity of v2=4.0m/s. Assume the collision is perfectly inelastic.
a)...