Conservation of momentum Definition and 752 Threads

Homework Statement A boy and girl are standing on ice skates and pulling on opposite ends of a rope. Find their velocities the instant they meet. How long did it take? Relative speed of approach is 2 m/s mass of boy = 60kg mass of girl = 50kg distance = 5m Homework Equations...

Regarding momentum, and the "Law of conservation of linear momentum", my book states that it's more general than mechanical energy, since mechanical energy is only conserved for conservative forces, while linear momentum is conserved independent of the forces, as long as the sum of external...

What does having no external force on a closed system mean? For example if I have 2 objects colliding. One travels at a constant speed while the other travels with a constant acceleration. In this case is an external force being applied on the system? If so, only the m1u1+m2u2=m1v1+m2v2 can be...

Homework Statement A 1200kg car traveling initially with a speed of 25m/s in an easterly direction crashes into the rear end of a 9000kg truck moving in the same direction at 20m/s. The velocity of the car right after the collision is 18m/s to the east. 3.4.1) What is the velocity of the...

[b]1. Somebody help explain how to do this for me, am not looking answer, an explanation so i can solve it would be great. A space vehicle traveling at a velocity of 7000km/h separates into two sections of mass 1100kg and 200kg. the two parts continue moving in the same direction with the...

Homework Statement Football player 1 with a mass of 110kg is moving at 8.0m/s [S] when he crashed into football player 2 with a mass of 105kg, moving at 12m/s [N]. During the tackle, football player 1 hangs onto football player 2, giving them the same velocity during the 0.3 second...

Basically, when a natural frequency acts on coke bottle, It resonates. During the resonance, the lump of air in neck of it goes under simple harmonic motion. It goes in and out the bottle, increasing and decreasing pressure of cavity of coke periodically. When air goes inside the bottle, the...

A 15 g bullet is fired is fired with a velocity of 220 m/s from a 6.5 kg rifle. What is the recoil velocity of the rifle? That is the problem I think i use the formula... This half of the equation equals zero due to the initial velocity equaling zero = Mass of the gun*Velocity of the...

Homework Statement An 800 kg airplane traveling at a velocity of 120 m/s [30o N of E @ 20o above the horizon] collides with a stationary 1200 kg helicopter. If the velocity of the airplane after the collision is 65 m/s [40o N of E @ 60o above the horizon] what is the final velocity of the...

Allover the web i am only seeing a statement similar to this: "Pair production is not possible in vaccum, 3rd particle is needed so that conservation of momentum holds." Well no one out of many writers shows, how to prove this matematically. So this is what interests me here. First i wanted...

Homework Statement Bronco dives from a hovering helicopter and finds his momentum increasing. Does this violate the conservation of momentum? Homework Equations p(before) = p(after) The Attempt at a Solution no, this does not violate the c.o.m, because it is a closed system of...

Homework Statement If a Mass let's say a Ball Bearing A with a velocity of 2ms-1 and a mass of 2Kg hits two other ball bearing B & C which is not moving with ball bearing B & C each has a mass of 1kg each. What will happen to ball bearing B & C? Please see attached picture i have the question...

Block 1 moves with speed of 10m/s to right. It hits block 2 which has twice the mass of block 1 and speed of 5m/s to right. compute the magnitude and direction of block 1 for a perfectly elastic collision. solution: u1 = 10m/s u2 = 5m/s m1v1 + m2v2 = m1u1 + m2u2 ----> v1 + 2v2 = u1 + 2u2 ...

Hi, I was wondering how one could know when velocity would be in the opposite direction in a momentum question. For example, two skaters are skating together (as one) at the same speed. Skater A pushes skater B and B moves at 13m/s. Find the speed of skater A. I found it and it's the...

Conservation of momentum does not hold true? Homework Statement Here is the problem. State 2 is shown in the picture, it is right before impact. State 3 is after impact. I used conservation of momentum of the entire system (rod and table. However as you can see it shows us that the...

Homework Statement A truck (4 000 kg) runs a red light and enters an intersection traveling at 81 km/h [E]. The truck collides with a car (2 000 kg) that was traveling at 54 km/h [N20oW]. Immediately after the collision the truck was traveling at 60 km/h [N 30o E]. Determine the velocity...

Two titanium spheres approach each other head-on with the same speed and collide elastically After the collision, one of the spheres, whose mass is 300 g, remains at rest. What is the mass of the other sphere? What i did: m1v1 + m2v2 = m1u1 - m2u2 v1 = 0 b/c at rest m2v2 = m1u1 - m2u2 m2v2...

conservation of momentum, elastic collision, find other mass? help! Two titanium spheres approach each other head-on with the same speed and collide elastically After the collision, one of the spheres, whose mass is 300 g, remains at rest. What is the mass of the other sphere? What i did...

Hello, Here is the situation I have been pondering: A person is sitting in a shopping cart at rest. By throwing their weight forward they are able to cause the shopping cart with them inside to move. My question is how this works. If momentum is conserved unless an external force acts...

Homework Statement a hockey player of mass 80 kg was skating at a velocity of 7.5 m/s [E 20 S] when he accidently hit a linesman who was just standing on the ice. The mass of the linesmass is 90 kg and his velocity after the collision was 3 m/s [E 30 N] find. a) the velocity of the hockey...

conservation of momentum?? Homework Statement A 45.0 kg girl is standing on a 156 kg plank. The plank, originally at rest, is free to slide on a frozen lake, which is a flat, frictionless surface. The girl begins to walk along the plank at a constant velocity of 1.51 m/s relative to the...

Homework Statement A 0.750kg block of wood is attatched to a spring with k = 300N/m. A 0.0030kg bullet is fired into the block, and the spring is compressed 0.102m. Calculate the velocity of the bullet before the collision. Is this elastic or inelastic? Homework Equations How do you do...

Homework Statement A man aims his gun vertically and shoots a 0.245 kg target, which is positioned on a telephone pole. The bullet has a mass of 0.055 kg and is traveling at a velocity of 850 m/s upwards just before it hits the target. The bullet passes through the target, emerging with a...

elastic collision with Conservation of momentum problem? i need help with part b. Two titanium spheres approach each other head-on with the same speed and collide elastically, After the collision, one of the spheres, whose mass (m1) is .3 kg, remains at rest. (a) What is the mass of the other...

I won't go into all the details but, to summarize, I'm planning on writing something on the philosophy of science and I was wondering if it's possible to deductively prove, that is without the use of observation or experience, the conservation of momentum. I know that it's possible to prove it...

In Fig. 9-58a, a 3.50 g bullet is fired horizontally at two blocks at rest on a frictionless table. The bullet passes through block 1 (mass 1.20 kg) and embeds itself in block 2 (mass 1.80 kg). The blocks end up with speeds v1 = 0.630 m/s and v2 = 1.40 m/s (Fig. 9-58b). Neglecting the material...

Homework Statement I am having difficulty understanding why in 2.1 Worked Example Coal Car on page 3 One can use the initial time as time = 0, but 2.2 Worked example on page 4 they start the initial time at an arbitrary time t. Homework Equations The Attempt at a Solution

Homework Statement Example 17.5.1 page 9 : I understand everything but one assumption that is made. " We can use this to determine the speed of the larger piece after the collision. Since the larger piece takes the same amount of time to return to the ground as the projectile originally...

I'm doing the prelab questions which require conceptual questions, not so much of math. The experiment is a typical ballistic pendulum lab - you'd shoot a paintball twoard a pendulum bob, and you measure the height the pendulum bob reaches after collision to calculate the related velocities...

Hi, I'm new to this forum. So I do not understand how, in an inelastic system, momentum is conserved. Consider this problem: Tarzan swings from a branch 4 meters up and picks up jane how far can he swing up the other side? He weighs 100kg and is standing still on the branch. He jumps...

Homework Statement Show that you can measure the magnitude of the velocity vectors which have units of distance/time with a ruler that measures distance, if a certain condition is met. What is this necessary condition.Use the Equation and Figure to prove below that this can be done...

Homework Statement A 1500-kg car is traveling north at 25 m/s when it strikes a 2000-kg car traveling east at 20 m/s. The cars stick together after the collision. What is the final velocity of the two cars? Homework Equations m1v1 + m2v2 = (m1 + m2)vf The Attempt at a Solution...

Conservation of Momentum? An unstable nucleus of mass 2.7 x 10-26 kg, initially at rest at the origin of a coordinate system, disintegrates into three particles. One particle, having a mass of m1 = 1.0 x 10-26 kg, moves in the positive y-direction with speed v1 = 4.8 x 106 m/s. Another...

Homework Statement Two particles A and B each of mass m are attached by a light inextensible string of length 2l .The whole system lies on a smooth horizontal table with B initially at a distance l from A.The particle at end B is projected across the table with speed u perpendicular to...

Homework Statement If a 30 g bullet is shot with a velocity of +300 m/s from a 7.5 kg gun, what is the recoil velocity of the gun? m1 = 0.03 kg v1 = 300 m/s m2 = 7.5 kg Velocity initial for both objects is 0.0 m/s Homework Equations (m1 + m2)(v) = (m1v1) + (m2v2) The Attempt...

A boat is 4 m long and there is a person standing on one end of it. He walks across to the other end of the boat. The mass of the person is 70 kg and the mass of the boat is 200 kg. Find the distance moved by the boat. Not very sure of my answer. Need help solving this.

I know this question is probably fairly basic but I had a hard time finding an answer on google. Does a single atom vibrate/jiggle/oscillate if it has a temperature (ie is not at absolute zero)? Is this vibration random in direction? If it is random, wouldn't this violate the law of...

In situations where the momentum of particles is only known to some degree of certainty, what can you say about the total momentum of the system? Is it only conserved to an extent that it always falls in a certain range?

Hi everyone! I need some examples about Conservation of the quantity of motion and of the momentum of the quantity of motion to verify that these physical quantities are conserved in isolated environment. Sorry for my bad english

Homework Statement A spaceship of mass M is traveling in deep space with velocity vi = 20 km/s relative to the Sun. It ejects a rear stage of mass 0.2 M with a relative speed u = 5 km/s. What then is the velocity of the spaceship? Homework Equations conservation of momentum, p = mv let U be...

Sir , Can you please explain me " The conservation of mometum " with an example ? I am not able to understand the concept of CONSERVATION OF MOMETUM . So please help me Sir . I will be very thankful .

Homework Statement Two Cars Yellow: Moving South Green: Moving West Green car stop in center of intersection and gets hit on from south bound Yellow Car They collide, at intersection, find initial velocity, impact velocity and momentum (this confuses me) Yellow Mass - 1356 kg Green...

In a collision the colliding particles will in general have different velocities at different instants of time. Overall this means that the particles can easily cover different distances during a collision and thus have different amounts of work done on them. My question is: Will the difference...

Hello, I am having trouble understanding this short problem from a Kaplan SAT II prep book. Here it is: A 60 kg man holding a 20 kg box rides on a skateboard at a speed of 7 m/s. He throws the box behind him, giving it a velocity of 5 m/s. with respect to the ground. What is his velocity...

A body with a mass of M is on a friction-free horizontal floor. The shape of the body is a half circle with a radius of R. A mass of m is put at the left edge of M and is released from rest. the mass m rolls on the half circle with no friction. Is there conservation of momentum during the...

Homework Statement Under some circumstances, a star can collapse into an extremely dense object made mostly of neutrons and called a neutron star. The density of a neutron star is roughly 10^{14} times as great as that of ordinary solid matter. Suppose we represent the star as a uniform, solid...

I am confused over the law of conservation of momentum. The definition says that "if there is no external force on the system then there is no impulse and the momentum is unchanged" However under the definition of Impulse Note "F is for all external forces including forces due to gravity and...

Two particles A and B of mass 4 kg and 2 kg respectively are connected by a light inextensible string. The particles are at rest on a smooth horizontal plane with the string slack. Particle A is projected directly away from B with speed um s−1. When the string goes taut the impulse transmitted...

Hey guys I've a theory that my physics lecturer wants me to prove, basically I have to prove the conservation of momentum which is easy enough but it's in a specific situation which happens to be a bouncing ball. So obviously I know relevant SUVAT equations and I know how to work out change in...

We know that the reason energy and momentum are conserved is b/c of Noether's theorem...time translational invariance implies energy conservation and space translational invariance implies momentum conservation. Now in a curved spacetime you can still form conserved quantities - energy and...