What is really momentum?
142999
Momentum refers to the quantity of the motion that the object have.....It is mainly " MASS IN MOTION "..It depends on mass and velocity....momentum = mass * velocity...or momentum(P) = mass(M) * velocity(V)....Its is a vector quantity...
44667
You have a contradiction in your statement.  Static friction implies no movement but velocity is movement.  \n\nIf you mean the velocity of an object in dynamic equilibrium has a result of a frictional force (kinetic though) like sliding a block across the floor then you have to know the amount of work put into the system.  Then use work-kinetic energy theorem.
1081985
This depends on whether you choose to consider the ball as a whole or as a conglomeration of individual particles.\n\nThe ball as a whole should have no momentum, since it has zero velocity. However, it may have potential energy if it is some height off the ground.\n\nThe particles in the ball have momentum because they are moving. Likewise, they also have kinetic energy, and potential energy from their height and the electromagnetic and nuclear forces.
567053
Wind is the motion of microscopic particles from an area of high pressure to an area of low pressure.  You can feel the particles bumping against your skin, but they are too tiny to see.  Try this:  sometimes you can see light ripples from heat rising off the ground.  This is light hitting a medium (air) and being momentarily refracted from particle motion.  In this case, you can see wind!
620382
Horizontal momentum is conserved throughout the problem. i.e., when half the mass fell downwards, all of the horizontal momentum must be carried in the second.\nThere's too much missing information for me to go farther than that...
69398
In some sense, it could be made up of individual particles.  But if you break down the particles far enough, they start to take on properties of waves as well as particles.  But the question is, if they are waves, what is there to do the waving?\n\nIf we observe the particles very closely, we can determine their exact positions - but the more precisely we determine their positions, the less we know about their momentum!  We can only draw a graph to represent the probability of a given particle's momentum _if_ it happened to be at a particular position, and there does not seem to be any way to exactly predict what its position or momentum might be at any given point in time, without measuring it.\n\nSo it could be that matter does not exist at all, unless it is being measured, or observed.  Could it be that what matter is made up of is...mind?
735972
Conservation of energy and momentum basically means that energy is never created or destroyed, and same with momentum. It has to come with somewhere. If energy or momentum leaves one system, it must enter another system. If energy appears in a system, it had to have come from one. Momentum is never really gained or lost, and same with energy -- it is simply transfered from one body to another. An elastic collision is one in which no kinetic energy is lost, all of it is transfered directly from one system to another.. In an inelastic collision, some of the energy is transfered to a third system (via sound waves, heat energy, or other such energy loss). In this case of an inelastic collision, the total kinetic energy of the two bodies before, is not the same as it is afterwards. The difference in these values would be the energy "lost" from these systems that was tranfered elsewhere.
237074
Yes, but you notice the rubber ball is going slower now. Its because part of the momentum has been transfered from the ball to the sidewalk (eventually tranfered to the Earth itself).  This is called transfer of momentum.
1042891
They don't call it a Law for nothing you know.\nWherever you look, you will always see an action-reaction paired up.  Newton's 3rd Law fits nicely in with another law which we know holds true in all cases...the Law of conservation of momentum.
641758
A better question is why do we feel ourselves moving on a lift or bus.\n\nOnly accelerations can be felt, not motion at a constant velocity. Einstein showed that motion at a constant velocity doesn't even have any meaning unless it is measured "relative" to some "stationary" observer, and even "stationary" has no meaning. But enough of that.\n\nEinstein also showed that acceleration is the same as gravity in that they can both be felt, and cannot be distinguished from each other unless you can look out a window. If you are in a closed box with no window, you cannot tell if you in a gravitational field or are accelerating.\n\nWhen a bus is traveling at a "constant" velocity, you in it are actually being accelerated in all different directions all the time as the bus bounces around. If the bus was traveling on a perfectly smooth surface at constant velocity, and had no windows, with no accelerations of any kind, you would not know you were moving.\n\nSame with the lift. You can feel only the accelerations up or down. If the lift is traveling perfectly smoothly at constant velocity with no accelerations, you would feel nothing, except that the pressure in your ears would tell you whether you are going up or down.
57662
Very super question! Yes the answers above are right. Action-Reaction, sure enough. But you have asked what is totally QUESTION NUMBER ONE in physics. It's an exciting question which many teachers secretly don't understand and so their students get this hazy idea and kind of go thru the motions. Here's a way to remember and understand through a nutty story.\n\nWow, it is so basic, that it took a super-genius, I mean way smarter than Einstein, to figure it out. A good old farm boy, astrologer, magician & alchemist, religious fanatic, mathematician and all around kook. Yep. Sir Isaac Newton. You gotta wonder what kind of parents would name their kid "Sir"\n\nWell we all know what a force is, it is a sort of push or pull -- think of it as something that changes or *tries to change* the motion of stuff.\n\nNewton first figured out that if you leave a thing alone, or if the pushes and pulls on it cancel out, then it will sit there like a lump. Like those drivers wearing hats, and like sit there after the light has already turned green two minutes ago.\n\nOr else a thing will keep moving in the same straight line direction and speed like those drivers wearing hats who go 40 mph on the expressway with their turn signal blinking on and on. This is known as "THE HAT LAW".\n\nAll was well until he noticed that things move faster in an amount equal to how much you bully them or push them around. Twice the force, twice the fasterness and fasterness (also known as acceleration). This is called the "YOU BIG BULLY LAW".\n\nThen he discovered a fly in the ointment. His HAT and BULLY laws didn't really explain all that much. Something was gumming up this beautiful theory. We call it MASS and it is still an unknown mystery as to what it really is. So we vaguely call it the amount of stuff or matter in a thing.\n\nSo he found out that for a certain force the faster-isity (acceleration) is cut in half if you double the mass. The bully has to push twice as hard to fasterize two little kids. So he was like "I'll just add that in, and all will be cool". The "YOU BIG BULLY LAW" and "THE HAT LAW" totally did it all. Wa ta da babee!\n\nBut then Newton had a road accident. He was gunning his Harley over London bridge at like 250 when a bug hit him in the mouth and knocked out one of his wooden teeth. He was all "Why am I so in pain?". And the bug as it squooshed said "Help! I'm a bug!"\n\nSo spitting out the splinters of his wooden tooth and the splattered bug, he had this revelation. He realized that because he was moving so fast, and the bug slowed down so fast, that even a eentsy mass like a bug was like taking a hammer to his tooth.\n\nHe noticed that the force was equal to the mass of the bug times the speed of impact all happening in a brief moment. Since Newton spoke Latin (he was the love child of Joe Newton and an Italian governess) he wrote "Fastus buggus ina momentum hurtus like crazy." Today we call this "momentum". It is just "mass times speed" or "force times a small moment of time".\n\nAnd he realized that the bug smashed up his tooth, but also that the bug was squashed (like a bug) because they were trading the EXACT same amount of momentum. The force on the tooth by the bug in the moment of time was PRECISELY equal to the smacko-ing the tooth used to stop the bug dead.\n\nHe said "Hey, like he broke my tooth, but I killed him soooo dead!" He did the math and found that the force of the bug on the tooth was equal to the force of the tooth on the bug!\n\nNo way did the two equal forces cancel, after all, his tooth was hammered to splinters, and the bug was flattened. They were equal and opposite, but since one was on the tooth, and the other force was on the bug they did serious damage! Today we call this the "HELP I'M A BUG" law.\n\nNow our man 'Zack was all set. He wr
549267
Lets say your mass(not weight) is 10kg. and you are running at the speed of 10m in 1 sec(10m/s).\nSo your momentum is mass x velocity = 10kg x 10 m/s = 100kgm/s\nSo momentum of a body is the product of its mass and velocity.\n(use this formula to calculate the momentum of a body)\n\n\nForce is that physical cause that changes the state of rest or of motion of a body.\nF= ma; F is force, m is mass of the body on which the force is applied, and 'a' is the accalaration of the body with mass m.\nYou use this formula to calculate the force on a body, all you need to do to find it out is multiply the accelaration and the mass of the body.
857410
Actually, the wall having no K.E. is okay, since the speed of the ball is the same before and after the collision. Momentum IS transfered to the wall and the earth supporting it but the mass of the wall (and earth) is so great that the corresponding change in velocity is undetectable...
730275
It's called 'impulse' and any good, lower division, physics book will have an explanation of what it is and how it works.\n\n\nDoug
82353
the classical def of the momentum is indeed p=mv, however, for  massless particles, this def no long applies, for the photon for instance, the momentum is given by\np=h/lambda, where h is the planck constant and lambda, the wave length\nIn that case, energy is given by E=hv, v bieng the frequency of the photon (v=c/lambda)
498603
Eggman is good except for one point: velocity is a vector not a scalar.  He was right that velocity was a speed and direction.  He just used the wrong term.\n\nAnother example would be that of a pendulum.  When the pendulum bob is at the peaks on either side, it is experiencing acceleration, but it has zero velocity for the instant it is at either peak.\n\nThis is actually the same as throwing a ball up in the air, and the ball stops for an instant at the very top of its path.  The only difference is the pendulum keeps going.  The point is, the peaks of a pendulum, and the peak of a ball being thrown straight up into the air are really the same thing happening.
666644
I don't know how so many people are confusing the first law of motion with the second law of motion. People, she's asked for the second 'theory' of motion, which is to be understood, of course as the second law of motion. Which states that the rate of  change of momentum is directly proportional to the impressed force and takes place in the direction of the force. \n\nThe proof of that cannot be derived from first principles, as it is one of the first principles itself. Of course, for a special case in which the system mass is constant, it does reduce to F = ma, but that is really elementary.