Information about Impact Force
An impact force is a high force or shock applied over a short time period. Such a force can have a greater effect than a lower force applied over a proportionally longer time period.
for a mass m accelerating at a, then assuming an ideal system, we can set the impact force as,
for a time interval dt.
For example, a train that weighs 1 kg moving at 500 m/s and that hits a 'perfect' steel wall where it uniformly decelerates from 500 m/s to 0 m/s in .02 seconds, has an approximate impact force of 25000 N. Thus, a body which decelerates more quickly has a greater effective impact than one which decelerates more slowly.
Theory
At normal speeds, during a perfectly inelastic collision, an object struck by a projectile will deform, and this deformation will absorb most, or even all, of the force of the collision. Viewed from the conservation of energy perspective, the kinetic energy of the projectile is changed into heat and sound energy, as a result of the deformations and vibrations induced in the struck object. However, these deformations and vibrations can not occur instantaneously. A high velocity collision (an impact) does not provide sufficient time for these deformations and vibrations to occur. Thus, the struck material behaves as if it were more brittle than it is, and the majority of the applied force goes into fracturing the material. Or, another way to look at it is that materials actually are more brittle on short time scales than on long time scales.Applications
- A nail is normally pounded with a series of impacts, each being a single hammer blow. These high velocity impacts prevent friction with the wood on the sides of the nail from retarding the forward motion of the nail.
- A pile driver does the same thing, on a much greater scale.
- An impact wrench is an analogous device designed to impart torque impacts to bolts to tighten or loosen them. At normal speeds, the forces applied to the bolt would be dispersed, via friction, to the mating threads. However, at impact speeds, the forces act on the bolt to move it before they can be dispersed.
- In ballistics, bullets utilize impact forces to puncture surfaces that could otherwise resist substantial forces. A rubber sheet, for example, behaves more like wood at typical bullet speeds. That is, it ruptures, and does not stretch or vibrate.
Example
Since
for a mass m accelerating at a, then assuming an ideal system, we can set the impact force as,
for a time interval dt.
For example, a train that weighs 1 kg moving at 500 m/s and that hits a 'perfect' steel wall where it uniformly decelerates from 500 m/s to 0 m/s in .02 seconds, has an approximate impact force of 25000 N. Thus, a body which decelerates more quickly has a greater effective impact than one which decelerates more slowly.
External links
- Application to mountain climbing: http://www.impact-force.info/anglais/impact1.html
Also See
In physics, force is an action or agency that causes a body of mass m to accelerate. It may be experienced as a lift, a push, or a pull. The acceleration of the body is proportional to the vector sum of all forces acting on it (known as net force or resultant force).
..... Click the link for more information.
..... Click the link for more information.
A mechanical or physical shock is a sudden acceleration or deceleration caused, for example, by impact, drop, earthquake, or explosion. Shock is a transient physical excitation.
Shock is usually measured by an accelerometer.
..... Click the link for more information.
Shock is usually measured by an accelerometer.
..... Click the link for more information.
nail is a pin-shaped, sharp object of hard metal, typically steel, used as a fastener. Nails for specialised purposes may also be made of stainless steel, brass or aluminium.
..... Click the link for more information.
..... Click the link for more information.
A hammer is a tool meant to deliver blows to an object. The most common uses are for driving nails, fitting parts, and breaking up objects. Hammers are often designed for a specific purpose, and vary widely in their shape and structure.
..... Click the link for more information.
..... Click the link for more information.
pile driver or piledriver is a mechanical device used to drive piles into soil to provide foundation support for buildings or other structures. The term is also used in reference to members of the construction crew that work with pile-driving rigs.
..... Click the link for more information.
..... Click the link for more information.
An impact wrench (also known as an air wrench, air gun, or just gun in some contexts, as well as rattle gun in some countries) is a socket wrench power tool designed to deliver high torque output with minimal exertion by the user, by storing energy in a
..... Click the link for more information.
..... Click the link for more information.
Ballistics (gr. ba'llein, "throw") is the science of mechanics that deals with the motion, behavior, and effects of projectiles, especially bullets, gravity bombs, rockets, or the like; the science or art of designing and accelerating projectiles so as to achieve a
..... Click the link for more information.
..... Click the link for more information.
acceleration is defined as the rate of change of velocity, or, equivalently, as the second derivative of position. It is thus a vector quantity with dimension length/time². In SI units, acceleration is measured in metres/second² (m·s-²).
..... Click the link for more information.
..... Click the link for more information.
kilogram or kilogramme (symbol: kg) is the SI base unit of mass. The kilogram is defined as being equal to the mass of the International Prototype Kilogram (IPK), which is almost exactly equal to the mass of one liter of water.
..... Click the link for more information.
..... Click the link for more information.
The newton (symbol: N) is the SI derived unit of force, named after Sir Isaac Newton in recognition of his work on classical mechanics.
..... Click the link for more information.
Definition
A newton..... Click the link for more information.
The Charpy impact test is a standardized high strain-rate test which determines the amount of energy absorbed by a material during fracture. This absorbed energy is a measure of a given material's toughness and acts as a tool to study brittle-ductile transition.
..... Click the link for more information.
..... Click the link for more information.
Package cushioning is used to help protect fragile items during shipment. It is not uncommon for a transport package to be dropped, kicked, and impacted: These events may produce potentially damaging shocks.
..... Click the link for more information.
..... Click the link for more information.
Izod impact strength is an ASTM standard method of determining impact strength. A notched sample is generally used to determine impact strength.
An arm held at a specific height (constant potential energy) is released. The arm hits the sample and breaks it.
..... Click the link for more information.
An arm held at a specific height (constant potential energy) is released. The arm hits the sample and breaks it.
..... Click the link for more information.
A mechanical or physical shock is a sudden acceleration or deceleration caused, for example, by impact, drop, earthquake, or explosion. Shock is a transient physical excitation.
Shock is usually measured by an accelerometer.
..... Click the link for more information.
Shock is usually measured by an accelerometer.
..... Click the link for more information.
This article is copied from an article on Wikipedia.org - the free encyclopedia created and edited by online user community. The text was not checked or edited by anyone on our staff. Although the vast majority of the wikipedia encyclopedia articles provide accurate and timely information please do not assume the accuracy of any particular article. This article is distributed under the terms of GNU Free Documentation License.
Herod_Archelaus
