# Read about momentum conservation | 52 Discussions | Page 1

1. ### A uniform rod allowed to rotate about an axis and then it breaks

A uniform rod AB of length ℓ is free to rotate about a horizontal axis passing through A. The rod is released from rest from the horizontal position. If the rod gets broken at midpoint C when it becomes vertical, then just after breaking of the rod. Choose multiple answeres from the below...
2. ### Find the magnitude of V1'

I know how to solve along x and y axis but i can't think of how to start solving in the dricection on m1.
3. ### Forces - Space Shuttle Takeoff Calculations

Homework Statement [/B] The total mass of a space shuttle and its launch vehicle is M=2000t. a) What must be the minimum size of the thrust force, to make the rocket move? b) The actual thrust of the rocket is F=30MN. What is its acceleration in the beginning? c) Assume that a mass of a...
4. ### B The physics of a Zipline

Hey! im new on the forum and I joined because I really enjoy physics but I have a horrible teacher. I was wondering if anyone could help me on a question how do I find the velocity at the end of the zipline? how do I find the momentum of the object going down the zipline after it is deployed...
5. ### Conservation of angular momentum

Homework Statement A rod of length D sits at rest on a friction less table. A ball of mass M strikes the end of the rod with a speed V and rebounds with a speed 3v/4 causing the rod to rotate counterclockwise around a fixed axis at one end. The rotational inertia of the rod is I Homework...
6. ### Other I can't solve questions related to conservation of momentum

I'm a passout from school taking a gap year. I find the concept of conservation of momentum exceedingly difficult. Each question - and sometimes each part of a question, if a question has different parts - requires us to choose different systems each time. I look at the solution, and think I...
7. ### Analyzing Elastic Collisions w/ Conservation of Energy and Momentum

Homework Statement There is a 4 kg mass that has a speed of 6 m/sec on a horizontal frictionless surface. The mass collides head-on and elastically with an identical 4 kg mass initially at rest. The final speed of the first 4 kg mass is: (a) 0 m/s (b) 2 m/s (c) 3 m/s (d) 6 m/s Homework...
8. ### A and C collide with B inbetween; AB elastic, BC inelastic

Homework Statement Three bodies A,B,C on frictionless surface masses= 1 kg each, Positions at time 0: A is at x=0,. B is at x=1, C is at x=2 (unit is 1 meter). velocities at time 0: A : 1m/s (to the right), B = 0 m/s, C = -1 m/s Assume sizes are uniform, or just ignore the sizes in...
9. ### Conservation of momentum - need help with understanding

I just want to state that i DID solve the problem. I just seek understanding of it. I'd be really grateful if someone could answer two of my questions at the end of this post. The problem I've solved here is just to show what I'm dealing with. 1. Homework Statement Object 1 is moving towards...
10. ### I Can a system have momentum without net velocity?

(I hope this post doesn't cross the border into the forbidden realm of quackery and speculation.) I have what seems like a simple question about Special Relativity but I haven’t seen it discussed anywhere, nor has anyone I've asked. Does the nonlinearity of the Lorentz factor provide a way...
11. ### Maximum amount of energy the neutron can lose

A 1 keV fast neutron (relative mass 1) in a moderator collides elastically with a helium atom He (relative mass 4) at rest. What is the maximum amount of energy the neutron can lose? My answer is 16/25 of 1ke but while deriving this answer I simply solved based on the question as if the...
12. ### Two spheres of are dropped to ground while in contact.

Two spheres of different masses are dropped to ground.They are in contact as one above the other and are of masses, let’s say m and 2m.They are dropped with velocity v - My question is if we can conserve momentum and if we can why?And how to find the final velocity of upper ball after...
13. O

### Energy Lost during elastic collision.

Homework Statement . True or False:[/B] For a completely elastic collision of two isolated masses the energy lost is ½μνr2 Where μ is the reduced mass of the system and νr is the magnitude of relative velocity between the two particles. Homework Equations The Attempt at a Solution Elastic...
14. C

### I Apparent violation of momentum conservation in EM

We have two cylindrical shells (with radii a and b and charges +Q and -Q) along the z-axis. There is a uniform magnetic field (in the positive z-direction) out to radius r from the z-axis. Because of the symmetry, the total field momentum is zero. Suppose we now connect the shells using a wire...
15. ### How to find the resultant force in a T tube section

Homework Statement So, I need to find the X and Y components of the force in the T section Homework Equations Due the fact that the problem dosn't ask for a specific force I couldn't think in any other equation to use, because even tough there is Pressure and Gravity acting I need to...
16. ### Conservation of Momentum Problem

Homework Statement The same horizontal force is applied separately to two objects initially at rest on a horizontal, frictionless surface. Object A has less mass than object B. In each case the force is applied for the same length of time. Which of the following statements is true after the...
17. ### Collisions -- conceptual questions

Homework Statement Let two particles of equal mass m collide. Particle 1 has initial velocity v, directed to the right, and particle 2 is initially stationary. A: If the collision is elastic, what are the final velocities v_1 and v_2 of particles 1 and 2? B: Now assume that the mass of...
18. ### Conservation of momentum - Vertical spring

Homework Statement A block of mass 200g is suspended through a vertical spring. The spring is stretched by 1.0 cm when the block is in equilibrium. A particle of mass 120g is dropped on the block from a height of 45 cm. The particle sticks to the block after the impact. Find the maximum...
19. ### Elastic/Inelastic collision upon Traincrash

Homework Statement A railway waggon of mass m=20t is travelling with v=18km/h. It then hits 10 other stationary railway waggons, with each one having the same mass of m=20t . (Friction is not being considered) Homework Equations a) Assume the 10 railway waggons are connected through strong...
20. ### B Momentum not conserved?

I remember throwing clay balls at walls in my childhood and observing them stick to the wall. In a more scientific perspective, considering the ball and wall as a system, I can say that the total momentum before collision is greater than 0. But then, after the collision, the kinetic energy of...
21. ### B Conservation of Momentum with Friction?

When reading lessons on the conservation of momentum, you usually see examples with colliding balls or something to that effect. These examples always seem to fail to mention friction. These balls will always come to a stop due to friction. How is momentum conserved when it is lost to friction...
22. ### Sign convention problem in momentum calulations

Homework Statement Particle A has a mass of 1kg and velocity 2x10^8m/s to the right and collides with a stationary particle B that has a mass of 4kg. after the collision, particle A moves to the left with a velocity(v) and particle B moves to the right with a velocity of 1x10^7 m/s. calcuate...
23. ### B A momentum question following collision

I think this is a basic question, at least I would hope so. If two identical motorcycles are going at the same speed but one has a lighter individual. If each individually collides with a stationary object and the driver is ejected. Who will go further and why?
24. ### I Is Canonical Momentum conserved?

Given a system of charged particles interacting with an EM field. Is the canonical momentum always conserved? If so, what is the associated symmetry? Thanks in advance.
25. ### Conservation of Momentum Spaceship Question

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 Equations The Attempt at a Solution I tried: pi=pf mivi=mfv2...
26. ### Finding velocity and momentum of a bullet and recoiling gun

Homework Statement A bullet leaves the barrel of a gun with a kinetic energy of 90 J. The barrel of the gun is 50 cm long. The gun has a mass of 4 kg, the bullet 10 g. (a) Find the bullets final velocity. (b) Find the bullets final momentum. (c) Find the momentum of the recoiling gun. (d) Find...
27. ### I Why are some systems defined with the name "variable mass"?

I do not get why systems such as the rocket in space are defined as "variable mass" since the mass of the system is not varying. The equation used for such systems $$\sum F^{(E)}=\frac{d\vec{P}}{dt} \tag{1}$$ (sum of external forces on the system equals the change in momentum) holds true only...
28. ### B Would momentum be conserved?

Would momentum be conserved on a cart if in one situation it is on an incline and the other it is on a flat surface(assuming it is pushed) I am confused because I thought that since gravity is an internal force, it is a conservative force. But then the final velocity of the cart would be...
29. ### Compton Scattering; Relation between scattering angles

Homework Statement Show that the scatter angles of the photon (θ) and electron (Φ) in the Compton effect are related by the relation: ##cot (θ/2 )=(1+\frac{hf}{mοC^2}) tan(Φ) ## Where f is the frequency of incident photon 2. The attempt at a solution I wrote down the equations of conservation...
30. ### (Tricky) Comet Picking up Mass - Differential Equations

Homework Statement A comet in deep space picks up mass as it travels through a large stationary dust cloud. It is subject to a gravitational force of magnitude Mf acting in the direction of its motion. When it entered the cloud, the comet had mass M and speed V. After a time t, it has travelled...