Why do you think the estimates of speed do not double when the skid marks from a car doubles in length?
440139
The skid marks will vary in length based on environmental conditions as well as the size of the car and speed (the momentum of the car) \n-A car on a wet road will slide further than a car a dry road.\n-A geo metro will not have as much momentum as a Hummer doing the same speed. Think of it like this:\nIf you to roll a bowling ball and a baseball at exactly the same speed and stop them both with your hand, which one would take more force to stop? The bowling ball, naturally would. So therefore, it is the momentum and not necissarily the speed that makes the difference. However, momentum is affected by speed so that is taken into account as well.
1044764
The law of conservation of momentum holds in this case.\n\nThe initial momentum of the system must equal the final momentum of the system.\nIn this case, we will call the "System" both cars.\n\nCar 1 has a mass (m1) of 1000 kg, velocity (v1) of 20 m/s.\nCar 2 has a mass (m2) of 800 kg and a velocity, in what we will call the negative direction, v2 = -30 m/s.\n\nThe total momentum (P) does not change.\n\nP = P1 + P2\n\nP1 = m1 * v1 = 1000 kg * 20 m/s\nP1 = 20000 kg m/s\n\nP2 = m2 * v2 = 800 kg * -30 m/s\nP2 = -24000 kg m/s\n\nP = 20000 kg m/s + -24000 kg m/s\nP = -4000 kg m/s\n\nSo the resulting 1800 kg mass will have a momentum of -4000 kg m/s, meaning that it will be traveling in the "negative" direction, AKA, South.\n\nP = -4000 kg m/s = 1800 kg * v_f\nv_f = -4000 / 1800\nv_f = -2.22 m/s\n\nThe resulting blob of the two cars which stuck together will be traveling -2.22 m/s South.
120276
The first thing you have to understand is that the speed of light in a vaccum is constant, no matter how fast you're moving, nor how fast the source of the light is moving. This is bizarre. If someone standing on a conver tosses a ball to you at 5 mph while you're standing on the corner, you'll see the speed of the ball as being 5 mph relative to you. But if you're driving at 15 mph and they throw it at you at 5 mph, the speed of the ball relative to you will be 20 mph. This is how most things work. But with light, no matter the speed of the source or yourself, you'll always measure the speed of light as being 299,792,458 metres per second.\n\nEinstein accounted for this by postulating his special theory of relativity, which says basically that the reason for this is because if you move really fast, three things happen: 1) time slows down, 2) mass increases, and 3) length in directions parallel to the direction of movement contract. If you take those three hypotheses, you'll also note that the concept of things being "simulatanous" is a relative term, meaning two observers moving at the same velocity (or moving at no speed relative to one another) will agree on which events are simultaneous and which are not. However, observers at different velocities will have different concepts of what is and isn't simulataneous--and yet THEY'RE BOTH CORRECT. It's pretty mind-blowing, but if you take all of these notions together, you get a consistent view of reality.\n\nThat's Einstien's SPecial Theory of Relativity. About a decade later he formed his far more complicated general theory of relativity.\n\nThe general theory says that Newton's view that gravity operates by exerting a force on a falling object is incorrect. Rather, by general relativty, a free-falling object that is in a vacuum has no forces acting on it at all. The movement of falling objects isn't due to force, but rather the curvature of space-time--massive objects actually curve the surrounding universe. In Newtonian physics, we regard there being three spacial dimensions (up/down, left/right, and backwards/forwards) and a single dimension of time. In general relativity, there are four dimensions of space-time. In Newtonian physics, a foce makes the earth orbit around the sun. In general relativity, the earth and the sun curve the surrounding space-time continuum, and both bodies move in a straight line through curved space, resulting in the perceived sense that one body is circling about the other. In Newtonian physics, light should not bend to gravity, because gravity affects massive bodies, and light has no mass. But in fact, light does bend around stars and such.\n\nGeneral relativity has been likened to a stretched sheet of elastic material, like a trampoline. Heavier objects sink more, and make the sheet curve about them, and light obejcts rolling across are deflected by this curving.\n\nGood luck understanding all that. Hope your head doesn't explode.
132222
Even if he is two cars behind, a radar gun can clock you at that distance. Radar guns are also extremely accurate.\n\nAnd also, even if you were going 90, thats still speeding.
162377
Decimals are great for real life applications. For example, if someone wants to know how a car going, it's easier to interpret 37.45 mph than 749/20 mph. It's just a hell of a lot more convenient. And I don't think anyone invented decimals, they just began to be commonly used.
8562
Just a quirk of history.  As to safety, there's really no difference.  In places where folks drive on "the other side," the driver is also "on the other side."  This means that visibility remains the same.
392779
Tthe moving object (mass) travels a distance of one meter in one second and that is an average velocity;that means the speed was not constant as it was moving. So dividing the distance travelled by the period of time traveled would give you only the average velocity.\nThe proof of this was given by a frenchman by the name Paris.\n\n However the final velocity would be twice the average velocity which would be two meters per seconds.dont feel bad I learned that in the 8th grade.
668935
it would be the exact same speed!  \nhere is an example. --------\n--if you are swerving on the road and going 50 mph. and then you stopped swerving, you would still be going 50 mph
837364
Not materially.  One dodge is to store the square of the distance -- you don't need to do the square root.
1074577
We have the same amount of energy in each case, however\n\n\n(A)Kinetic Energy (KE) car1 >0 , KE car2 =0\n50% damage. Energy is being shared equally (since the cars are identical) \n\n(B) KE car1 >0 , KE Wall =0\n100% damage. All energy is observed by the car since the wall is inelastic and immovable.  \n(C) KE car1 = KE car2 >0\n100% damage since both cars had the same amount of kinetic energy.\n\nIn reality the structure of the vehicles and the geometry of collision would determine the extent of damage.
333495
The scale would tell you that.  For example a hot wheels car is 1:64 so 1 inch on the hot wheel is 64 inches on the real car.
719425
ya, that one has the same dimension as that of time.see how that eqn is derived.you find distance covered by 'n' seconds then distance covered by (n-1) seconds.subtract.and you get the eqn.... but see wat is the difference b/w the time n and n-1. it is one second..this is the one that appeared in the eqn and confused you.is it clear?
969523
if they are both going at the same speed, then the mass,size of the wheel and other considerations have already been take in account, so they both should arrive at the same time.\nGod bless,\ngabe
293316
No biggie. I've personally had two cars in the air. \n\nIt just wasn't by choice...
863911
Because not everything is the same size & mass and going at the same speed, etc. Those attributes... vary.
264364
They are made to run faster so that they last longer when ran at the normal speeds in society. If cars were made only to go 65mph then they would stop working much sooner than a car that can go twice that speed.
445486
Because the up/down motion is independent of the side-side motion. The stone is already going at whatever speed the car is and that doesn't change. The only thing that changes is the up/down part of the motion. For someone outside the car, the stone looks like it goes along a parabolic arc, not just up and down.\n\nThis is related to the relativity of motion. If you are moving uniformly, it is impossible to tell whether you are moving or not unless you look outside the car.