Physic- Rotational Motion and the Law of Gravity:?
814690
The forces on the person are\n\nSFx = 0 = N - Fc\nSFy = 0 = Fs - m*g\n\nwhere SFx and SFy are the sums of the forces in the x- and y-directions, respectively, N is the normal (to the wall) force, Fc = m*v^2/r is the centripetal force, Fs = u*N is the friction force, m is the mass, and g is the gravitational acceleration.\n\nThese equations say that\n\nN = Fc = m*v^2/r = m*w^2*r\nu*N = u*m*w^2*r = m*g\n\nwhere w = v/r is the angular speed. Solving for the coefficient of static friction gives\n\nu = g/(r*w^2)
69030
Initially, the ball is pushed, it slides. There is no rotation, as stated in the problem/question. This means there is no rotation at all. That all the velocity is translational.\n\nFor this scenario think of the ball as a solid block that has been pushed and it sliding across the floor.\n\nAs stared, at some time (t1) the ball begins to roll.\n\nAt this time, the ball's motion is both rotational as well as translational. In other words, it rolls as well as moving forward. This motion is what takes place at the *contact point* of the ball to the floor.\n\nIf the ball rolls, it is not slipping.\n\nIndeed, the friction causes the linear motion to decrease, and eventually stop the ball.\n\nThe rotational motion of the ball is also undergoing friction. A rolling sphere's motion is very subtle and often misunderstood. By virtue of the ball's mass there is a very tiny (tiny is relative to the mass and material) flat spot between the ball and the surface upon which it rolls, whereby a small torque gives rise to a resistance of the motion. This is why a rolling sphere slows. But.....since there is friction, the velocity of translation, is related to that of rotation by the following:\n\nv^2 = 2gh/(1 + I/Mr^2)\n\nWhere M is the mass of the ball and "r" its radius, I its moment of inertia. This is common notation. If there is no rotation, then the moment of inertia term drops out (I = 0) and you are left with a velocity which is strictly that of a translating body......kind of like free-fall.\n\nIf the ball is given one initial push to give it the initial velocity Vo, then unless there is some other forcing function at work, friction will act to decrease the motion of the ball, and all said velocities thereof. None of the velocities will increase.\n\nIf you know of a situation where such a case can exist where the ball increases velocity without doing anything to it.....make sure you mention my name when you pick up the your Nobel Prize.\n\n:)
252215
2nd Law of motion:  the net force = the time derivative of the momentum vector.
555212
Yes, velocity is changing it's direction as well as magnitude. Acceleration due to gravity is acting downward.
901353
It would have been helpful if you had cited where Einstein said this.\n\nBut here's the deal...all motion is relative (which is why the theory is called the theory of "relativity")...relative to something or somethings.  Even things that seem to be perfectly still, like the tree in your front yard, are moving relative to something...relative to the sun, for example.  In other words, there is no such thing as an absolute motion relative to absolute zero velocity.\n\nWith all these motions (velocities) we have accelerations (v = at; a = v/t) that are, like their velocities, not absolute.  They, too, are relative.  So, as F = ma or F = mv^2/r = (m(v/t)^2)/r, the associated forces are relative.\n\nAs a consequence, there are forces acting on everything, even when none is readily apparent.  That tree, for example, has weight, which is one force.  But it also has a kinetic force (centripetal) due to its spin around the Earth and its revolution around the sun while on the Earth.  Then there's the motion of the solar system around the center of the galaxy, the motion of the galaxy through the universe, and the expansion of the universe itself.\n\nSo a single measured force is really the vector sum of all those other forces created by all those other motions.  So the notion that there is but a single force at work is "fictitious."  The good news is that the single force usually works in our observable world because we can ignore the effects of all those other forces.  But, alas, that is not the case in the relativistic world of near light speeds.  That is probably why Einstein would indicate what you claim he did.
998322
Lets make an enormous assumption to fill in the gaps.\nYou have a thing on a string of length L and spin it round at a certain rate of rotation. Keeping the rate of roataion what would the tangential velocity of the thing be if the string was shortened to L/2?\nIn this case the tangential velocity (= the radius x the angular velocity) will also halve.
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.
771534
The problem is about conservation of angular momentum.  The tricky part is (b). To solve this use this definition of angular momentum and draw a picture to find out the value of r sin θ\n\nThe angular momentum of a particle of mass m with respect to a chosen origin is given by vector product L = r x p= mvr sin θ
844498
You have uncovered one of the secrets of the universe. Simple Harmonic Motion (SHM) surrounds us in every aspect of the universe. It is the lowest common denominator. Even Newton got it slightly wrong in his First Law where he said that a body will continue in uniform motion until an external force acts upon it. There is nowhere in the known universe that gravity does not exist.\n\nConsider an air table which is flat and which extends in all directions by a million miles, and it rests on the earth. place a puck on it and give it a gentle nudge. It will move off in the direction you push it at an apparently constant velocity, however it will eventually stop and return to the point where it started because of the earth's gravitational field. It will shoot past and head off in the opposite direction until it stops again, being pulled back by the earth's gravitational field. It will continue this way forever (ignoring all friction), oscillating in simple harmonic motion. \n\nNewton's problem was that he was restricted to observing a very small portion of the SHM path, so it seemed linear.\n\nAnyway, congratulations, you are on the path to unlocking the secrets of the universe.
253742
Please take the time to\nvote for the best answer\n\nThank You!!\n\nRecall that an object of a certain mass moving with particular speed will have an associated kinetic energy  mass x speed2. An object spinning about an axis will also have associated with it a kinetic energy, composed of the kinetic energies of each individual part of the object. These individual contributions may be summed up to give an expression for the total kinetic energy of the spinning object: \n\nLook this up for more
310151
The Coriolis effect. If the Earth were not rotating, the effect would be a mysterious "fifth force" with no physical explanation. See the source for details. \nAccelerating frames are absolutely determined. The above references to relativity theory are completely incorrect; Newtonian theory equates frames with constant velocity, Einstein equates an accelerating frame with a local curvature (gravitation). This is all the two theories have to do with the badly referenced quotations above.\nThe amount of pseudoscience and bad science on these forums is strange, given the amount of knowledge freely available over the internet.
1001657
V= V(i) + AT Initial velocity plus acceleratin x Time\n\n\n   = V(i) + (F/m)T     Acceleration = Force/ Mass\n\nNote  use same system of units
905757
This is uniform motion, if it is going in a straight line at constant speed.\n\nIf there are no forces acting upon a body, and therefore no acceleration (remember F=ma) or change in direction, nor any change in angular momentum, the motion is uniform. If it were changing direction, accelerating or going round in circles then it is non uniform.
159555
law of gravity\nexploration of nature of light and laws of optics\nlaws of motion\n\nin general, physics
242501
Relative motion between objects was not new to Newton and his contemporary scientists.\n\nEvery experimental result proved and confirmed again and again Newton’s laws of motion even in the frames of reference moving relative to each other.\n\nLatter with the improvement in measuring technology and particles moving nearly equal to the velocity of light, their behavior contradicted Newton’s laws.\n\nEinstein with a firm belief that any physical law (including Newton's law) must be the same in any reference frame moving relative to each other postulated that speed of light is independent of the source of light.\n\nThis explained every experimental result well and obeyed Newton’s laws.\n\nThe only difference is that  the basic quantities mass , length and time which during Newton’s time was thought of absolute in the sense that  they will not change with the velocity of the frame in which they are , is now considered to vary with the speed of the reference frame, and the velocity of light is independent of the motion of the source.
989766
hey this is a very good question. \nthe circumference divided by 24 (i.e. hours) = angular velocity travelled in one hour. \nif the rotation changes suddenly or  it stops rotating suddenly then due to the inertia that every moving object carries will suddenly travel in the direction of rotation at exactly the angular speed of the earth. so ocean water will move all over the earth and the plates beneath the earth will shift causing severe earthquakes and the volcano will erupt from the gaps due the internal pressure. so all the movable objects will shoot. these objects will move in the direction perpendicular to the centre of the globe in the direction of the motion respectively. there after stopping , there would be more gravitational force exerting on the objects cause the earth while in motion , objects have centrifugal force that is why the weight is different at the time when earth stops rotating and due to the absence of the centrifugal force weight would be more. there day will be 6 months and the night would also be 6 months longer like the north/south pole.
79989
Still more theory than fact.\nIt is responsible for the force of gravity.