Collision, a normal phenomenon in our daily life, also is familiar by people in physics field.
As we can imagine, there are many interesting among collision cause our attention to think about what is this exactly about and how does is work or maybe why is that such as there maybe some neutron stars intensely hurtling in outer space or two small eggs hitting each other. Outer space is filled with infinite particles that maybe as small as things people cant find out or measure so far and collisions are mostly about those small particles moving and hitting.For example, light wouldn’t be so bright according to its mass and the reason that it delivers light is because collision — namely fraction – to produce photon and then integrate light. A collision is an isolated event in which two o more moving bodies exert forces on each other for a relatively short time.
Even though, many people would refer collision to accidents where there are object badly crashed, what my topic will be focused on are those phenomenon among physics world. Moreover, when scientists use the word of “collision”, they try to imply nothing about the magnitude of the forces.Collision was ever a hot topic drawing many physicists’ attention. After plenty of delving, physicists establish the momentum conservation law.
Collision is a typical characteristic in microcosm in physics. Fortunately, collision can be simply solved from difficultly by using momentum conservation law to explain the details. Collisions are divided into two types – elastic collision and inelastic collision – by measuring loss of kinetic energy in the collision. Elastic collision is defined as one in which there is no loss of kinetic energy in the collision.
As we can imagine in macroscopic aspect, any collision between objects will convert some kinetic energy to internal energy and other forms of energy. As a result, we can assume that no large-scale impacts are perfectly elastic. In reality, for example, any two different balls will have deformation as long as they collide to each other and end up being recovered perfectly. If there is no loss among this motion, the whole kinetic energy of two balls remains equally before or after collision.
Then this case is considered as elastic collision. However, this sounds like a little impossible in reality.And we can solve problems by sufficiently using some collision as elastic that they can be approximated. Collision between hard spheres may be nearly elastic, so it is useful to calculate the limiting case of an elastic collision.
The assumption of conservation of momentum as well as the conservation of kinetic energy makes possible the calculation of the final velocities in two-body collisions. In addition to inelastic collision, it is one in which part of the kinetic energy is changed to some other form of energy such as heat caused by fraction in the collisions.Although momentum is conserved in inelastic collisions, people cannot measure the kinetic energy through the collision because of some losing energy converted from kinetic energy. Two balls again, for instance, have deformation after hitting each other, but they cannot recover the original shape eventually according to truth that they might lost energy particularly heat from kinetic energy.
Consequently, the whole kinetic energy of two balls changes, for it after collision becomes less than that before collision.We regard this as inelastic collision. There is no difficulty to find examples of collision especially inelastic one such as a blob of oil drop on the ground and its shape completely changes also ending up sticking on the ground. In the natural world, most of collisions are inelastic collision.
In the middle of 17st century, there were many physicists including Galileo, Mariotte, Newton, Descartes, and Huygens trying to figure collision problems out by conducting series of experimentation on collision.As time went by, physicists concluded into laws about collision step by step even coming with a basic structure that is about conservation among motions – well-known momentum conservation afterward. In the modern day, collision plays a crucial role in science. Since scientists invented diverse techniques on an accelerator, they have been able to find more new particles by utilizing collision between particles with high energy.
New particles enrich scientists’ comprehension on microcosmic world and contribute in not only physics but also the others such as chemistry and biology.Momentum conservation always comes solving problems with elastic collision. Momentum is the product of the mass of multiplying velocity of an object. It is a vector quantity and a conserved quantity – namely there is no change of total momentum in a closed system.
Momentum can be defined as two groups – linear momentum and angular momentum. Momentum conservation law is widely used in physical field such as electrodynamics, quantum mechanics, quantum field theory, and also general re lativity. Conservation of linear momentum is easily used to calculate and solve simply elastic collision problems.It states that if no external force acts on a closed system of objects the momentum of the closed system remains constant.
Also, in an isolated system the total momentum will be constant: the change in momentum of one object must be equal and opposite to the change in momentum of the other object. Mathematically, In order to solve some common elastic collision problem, we can apply conservation of linear momentum in this working. Since momentum is considered conserved, the sum of the momenta before the collision must equal to sum of the momenta after the collision:Where u1 and u2 are the velocities before collision, and v1 and v2 are the velocities after collision. Moreover, in one dimension of collision, when the initial velocities are known, the final velocities can be worked out: From the equation above, if we know mass of m1 is much bigger than that of m2, the final velocities are approximately worked out: Another case is that when mass of m1 is equal to that of m2, the final velocities are worked out: From this result, we can tell these two objects which have same amount of mass switch each other velocity after they collide.
This phenomenon is also demonstrated by Newton’s cradle. As collision happens, people understanding how momentum works in the motion between objects should also know how to protect themselves from it. For example, people should not jump off their high-speed-moving automobile, for it is dramatically dangerous for their bodies. Even though people may see these kinds of action very cool in the movies, it definitely hard for them to protect themselves during a high-speed moving and it easy for them to get hurt from hitting by some objects with large mass.
If people are about to get into an accident, they should endeavor to slow down the automobile and use some protecting postures preventing from possible hurt rather than try to jump off the automobile. Besides, A Kansas State University physicist says fans can observe the elements of this science by simply watching the game. “The most obvious are collision that occur during a football game,” said Dean Zollman, professor of physics at K-State. “A person who is running into another person will respond on the speed, the direction and the mass or weight that the person has.
So if you want to tackle somebody and make sure they don’t go very far, it’s much better to tackle them head on than it is to tackle from behind,” he said. “If you’re behind the runner with the ball, then when you hit that person your momentum and his momentum go in the same direction. If the momentum are in opposite directions, then there’s going to be a stop at some point. ” Zollman says when a large lineman tackles a back who is usually somewhat smaller, the lineman doesn’t have to be going nearly as fast in order to throw the back in the opposite direction because the mass involved is much greater.
So the momentum of a lineman can be more even though he may not be running as fast. Recoil can be related to momentum theory too. It is the backward momentum of a gun when the gun is discharged. There are two conservation laws at works when a gun is fired: conservation of momentum and conservation of energy.
Assuming that the firearm and projectile are both at rest before firing, the their total momentum is zero. Immediately after firing, conservation of momentum requires that the total momentum of the firearm and projectile is same as before. So we can write this: Pf +Pp =0, Where Pf is momentum of the firearm and Pp is the momentum of projectile. In other words, we can easily draw out that the momentum of firearm is queal to opposite to the momentum of the projectile.
In addition, we can also work out its velocity by using conservation of momentum law: Mf x Vf = Mp x Vp, Where Mf is the mass of the firearm; Vf is the velocity of the firearm immediately after firing; Mp is the mass of the projectile; Vp is the velocity of the projectile immediately after firing. Collision and conservation of momentum are relevant to our life. The more we learn from them, the more we can enjoy our life.
