Conservation of momentum Definition and 751 Threads

Homework Statement An incompressible fluid of density ##\rho## flows steadily through a 2D infinite row of fixed shapes. The vertical distance between shapes is ##a##. Define station 1 as the space where velocity enters and station 2 where it exits. Also, velocity and pressure are constant...

So I read that the conservation of momentum is a result of: F1=-F2 <Newton's Third Law t1=t2 <Time in contact Therefore: F1*t1=-F2*t2 F=m(Δv/t) Ft=mΔv So we can conclude: m1Δv1=-m2Δv2 Therefore momentum is conserved. Now what force is this? Would it be the same normal force that exists when...

In an inelastic collision is the change in kinetic energy equal to the difference of final and initial momentum if one of the objects is initially at rest? For example: m1v = (m1+m2)Vf -----> 0 = (m1+m2)Vf - m1v1 1/2(m1+m2)Vf^2 - 1/2m1v^2 = (m1+m2)Vf - m1v1 Or totally wrong? Thanks!

If a car crashes with a stationary tree and comes to stop, we could say that the kinetic energy of the car was converted to heat and that the collision was inelastic. However, conservation of momentum dictates that momentum is still conserved. How would that be possible given that neither the...

If two photons traveling in the same direction but out of phase cancel each other out, what happens to the energy and momentum?

Homework Statement The mass of a spaceship is 10012 kg. The spaceship is at rest. Then one part of the ship with a mass of 1000 kg is ejected and emerges with a speed of 112 m/s. What is the speed of the other part? Homework EquationsThe Attempt at a Solution I tried: pi=pf mivi=mfv2 10012...

Homework Statement Two point masses m1 and m2 are coupled by a spring of spring constant k and uncompressed length L0. The spring is fully compressed and a thread ties the masses together with negligible separation between them. The tied assembly is moving in the +x direction with uniform speed...

Homework Statement After shooting a 28g arrow with an initial velocity of 92m/s[forward], an archer standing on a frictionless surface travels in the opposite direction at a speed of 0.039m/s. Calculate the combined mass of the archer and the bow. Given: **Subscript of 1 indicates values for...

How is conservation of momentum present in an airbag?

Homework Statement In the figure, a small 0.235 kg block slides down a frictionless surface through height h = 0.471 m and then sticks to a uniform vertical rod of mass M = 0.470 kg and length d = 2.36 m. The rod pivots about point Othrough angle θ before momentarily stopping. Find θ. Homework...

Homework Statement A disc of mass M and radius r is kept on a horizontal,frictional plane and is connected to a horizontal spring at the centre.A particle of mass m strikes the topmost point of the disc,tangentially and sticks to it.Assume that the mass of the particle is m and it's velocity is...

Homework Statement Homework Equations conservation of momentum 3. The Attempt at a Solution initially car_1 has not y momentum so \begin{equation} m_1v_1x=(m_1+m_2)v cos(θ) \end{equation} and car_2 has no x momentum \begin{equation} m_2v_2y=(m_1+m_2)v sin(θ) \end{equation} using...

I don't understand why the conservation of angular momentum can imply an acceleration, in absence of a force. Consider for istance planetary motion. The angular momentum \vec{L} of the planets is conserved and that means \mid \vec{L} \mid=mr^2 \dot{\theta}=mrv_{\theta} is conserved too...

Hi all, I'm having trouble working out how much energy will have to be dissipated in a test rig for a nail gun. From previous testing, I know that a test slug fired from the gun has a mean energy of 100J. I now want to design a test rig which can fire the gun repeatedly for 100,000 shots. I...

Homework Statement A railroad car moves under a grain elevator at a constant speed of 4.50 m/s. Grain drops into the car at the rate of 420 kg/min. What is the magnitude of the force needed to keep the car moving at constant speed if friction is negligible? Homework Equations U=V+dV-Vrel , U...

Homework Statement A 52kg man is on a ladder hanging from a balloon that has a total mass of 450kg (including the basket passenger). The balloon is initially stationary relative to the ground. If the man on the ladder begins to climb at 1.2m/s relative to the ladder, (a) in what direction does...

According to amperes force law two parallel wires with current flowing in the same direction will experience a magnetic force attracting them together. consider two 1cm long wires parallel to each other, separated by a distance of 1cm. Pass a current through both of the wires for the time it...

I wanted to know whether or not a perfect mirror would experience recoil when light reflects off it, and I also wanted to know whether or not light can cause a recoil during total internal reflection. I suspect that the recoil is negligible (Even with a normal mirror) and that you could easily...

Homework Statement The classic double ball drop question: a ball of mass m is placed directly above another ball of mass M, and assume that m is not negligible. Both balls are dropped simultaneously. Find the mass m such that, upon the second collision (m with M), M has a final velocity of...

Homework Statement Actually, my confusion originated from solving two different problems... 1) A point object of mass 'm' moving horizontally hits the lower end of the uniform thin rod of length 'l' and mass 'm' and sticks to it. The rod is resting on a horizontal, frictionless surface and...

Homework Statement A bob of mass m attached to an inextensible string of length l is suspended from a vertical support. The bob rotates in a horizontal circle with an angular speed ω rad/s about the vertical. About the point of suspension : (1) angular momentum changes in direction but not...

suppose a platform "P" is rotating about the z-axis wrt x-axis . another platform "Q" rotating about z-axis below "P" with same angular velocity wrt x-axis standing on Q , P is at rest wrt Q, After some time rotational inertia of P about z-axis starts changing with time standing on Q , P will...

Not a scientist, please be nice :) Let's assume I have a singe axis gyro (flywheel) spinning in space. I apply a force to a point which results in a change in pitch. I apply this force until the gyro is at 5* pitch and then stop. Will the gyro continue to change pitch after the force stops...

I am having trouble wrapping my head around a physics concept. If we roll solid sphere down an inclined plane it will reach the bottom at a different time than if we were to say, roll a hoop down the same inclined plane. This is because they have different rotational inertias, and so more of...

Moved this question from the quantum physics section to this section, since... Well it fits this section better since electrons apparently do obey conservation of momentum in the 'classical' sense. Why not produce thrust in microgravity with electrons? Plenty of harnessable electricity in...

Electrons have a theoretical rest mass. They can move at varying speeds through space, unlike photons. They ehxhibit quantum-characteristics in their behavior. If an electron collides with, say, an atom, does conservation of momentum apply in the classical sense or does measurable mass (an atom...

Homework Statement Consider a gun of mass M (when unloaded) that fires a shell of mass m with muzzle speed v. (That is, the shell's speed relative to the gun is v.) Assuming that the gun is completely free to recoil (no external forces on gun or shell), use conservation of momentum to show that...

Homework Statement A 1.0-kg standard cart collides on a low-friction track with cart A . The standard cart has an initial x component of velocity of +0.40 m/s , and cart A is initially at rest. After the collision the x component of velocity of the standard cart is +0.20 m/s and the x...

Homework Statement This lab I have the mass and change in distance measurements for inelastic collisions; and then we did an elastic collision one where we determined the mass and measured the times three of them simultaneously where we measured it as it bumped the car. So I am supposed to...

Homework Statement Two objects collide and bounce off one another. After the collision, object m1 = 2.74 kg moves off at 12.8 m/s at a heading of 295 degrees. Object m2 = 2.28 kg moves off at 12.8 m/s at a heading of 241 degrees. Initially, m2 was traveling at 11.1 m/s at a heading of 334...

Homework Statement A stationary nucleus undergoes radioactive decay. A beta particle and a neutrino are detected leaving the nucleus. What is the recoil velocity of the remaining nucleus? If the recoil velocity measured is significantly different from the calculated velocity, what conclusion...

let's look at force at the atomic level to understand the Newtons third law of motion. I'll use Helium atoms as an example. Now imagine we start with one atom HE2 stationary, and throw another atom HE1 at it.It is the velocity of HE1 that affects the motion of HE2 , because the system of these...

Homework Statement A photon with energy E collides with stationary mass m. They form a single particle together, what is this new particle's mass and what is its speed? Homework Equations Energy-momentum 4-vector P=(E, px, py, pz) Possibly P2=m2 The Attempt at a Solution Using 4- momenta, the...

i got in an argument with my physics teacher about a test question recently, and am still reluctant to abandon my logic. The question is a standard explosion problem, akin to this: A firework is placed in the midst of some motionless billiard balls. The firework goes off and the billiard balls...

So, i was on the plane going for oxford interviews and i was thinking about what i could be asked. While i was thinking i came up with this one. Suppose the Earth and the moon were at a distance α apart at rest, how long would it take for them to crash into each other. I'm only really...

Homework Statement [/B] A block of mass m is attached to a spring with a force constant k, as in the above diagram. Initially, the spring is compressed a distancex from the equilibrium and the block is held at rest. Another block, of mass 2m, is placed a distance x/2 from the equilibrium as...

Homework Statement https://scontent-sea1-1.xx.fbcdn.net/hphotos-xft1/v/t35.0-12/12414351_10206719685063143_386848762_o.jpg?oh=16c004481b7417fad921c37acc4942be&oe=56793416 Homework Equations Angular momentum: H= Iw Parallel axis theorem: Io = I + Md^2 Moment of Inertia of thin plate about it's...

Homework Statement Homework Equations m1v1+m2v2=m1v1+m1v1 after The Attempt at a Solution my answer = -1m1v1 because the wall is not moving so its velocity is 0 therefore m1v1 = m1-v1 after I put -v because it is the same just bounces in the opposite X direction I found somewhere...

Homework Statement sorry for the long question. Homework EquationsThe Attempt at a Solution I get everything up until it asks where the extra "half" of the power is spent. I do know that the extra half is referring to the "2" dK/dt. I have spent the last hour or so thinking about this...

Homework Statement I'm designing a device for changing a load position from vertical to horizontal. It has a wheeled frame (2) which allows an operator to transport the load after reorientation. The combined centre of gravity of a rotating platform (1) and the load moves forward due to...

Homework Statement We are trying to find out whether we can hit a weight ##m=3## kg up to a given ##h=15.24## meters with a hammer with a head of ##m=6## kg swung at ##v=10## m/s. Homework Equations KE=0.5mv^2 PE=mgh p=mv The Attempt at a Solution One solution is to even see if the energy...

Referring to the Law of Conservation of Momentum: How is momentum always conserved? In a non-isolated system, an external force causes a change in momentum, so that initial momentum isn't the same as final momentum. Wouldn't this constitute a situation where momentum is not conserved? Or, is...

A small block of mass m slides on a long horizontal table when it encounters a wedge of mass 2m and height h The wedge can also slide along the table. The mass slides up the wedge all the way to the top and then slides back down, never getting over the top. All surfaces are frictionless...

I've been a fan of this forum for a while, but never signed up for it, today I'm stuck on this problem and can't find anywhere other than Chegg but I don't have a premium account. 1. Homework Statement A meter stick is at rest on frictionless surface. A hockey puck is going towards the 30cm...

Homework Statement Two equal mass hockey pucks undergo a glancing collision. Puck 1 is initially at rest and is struck by puck 2 traveling at a velocity of 13 m/s[E]. Puck 1 travels at an angle of [E18N] after the collision. Puck 2 travels at an angle of [E4S]. Determine the final velocity...

Homework Statement A 1500-kg sedan goes through a wide intersection traveling from north to south when it is hit by a 2200-kg SUV traveling from east to west. The two cars become embellished due to the impact and slide as one thereafter. On-the-scene measurements show that the coefficient of...

Take the case of Atwood machine, Where the masses of blocks are m and m,now,another ball of mass m strikes one of the blocks with a speed v and sticks to it. Considering our system as blocks+ball+string connecting the blocks(no pulley),can we apply conservation of momentum? Please explain...

Homework Statement [/B] A shell of mass m and speed v explodes into two identical fragments. If the shell was moving horizontally (the positive x direction) with respect to Earth, and one of the fragments is subsequently moving vertically with speed v, find the velocity v of the other fragment...

Hi, Consider the conservation laws for an isothermal linear incompressible flow governed by the mass and momentum equation. The kinetic energy equation is then solved to see if energy conserved. Can anyone tell me if once it is shown energy is conserved, it implies that convergence is obtained...

Homework Statement A 48.0-kg boy, riding a 1.60-kg skateboard at a velocity of 5.80 m/s across a level sidewalk, jumps forward to leap over a wall. Just after leaving contact with the board, the boy's velocity relative to the sidewalk is 6.00 m/s, 7.40° above the horizontal. Ignore any friction...