Greetings from the new kid on the block I have a question: ( I've already done some work on this at the Physics 101 level ) Case of a physical object traveling at 240 meters/sec and having a mass of 100,000 kg meeting a stationary object of 2,000 kg ( inelastic collision ) My concern here is for what happens to the original object that was traveling at 240 m/s that is what consequences to this collision would there be ( obviously loss of speed, however, how much, and over what span of time ) Any help for a marginal student? Thanks in advance.
You don't have enough information here to calculate anything about the consequences to this collision. Here is a link that might help you out though. http://www.real-world-physics-problems.com/inelastic-collision.html
On the alleged insufficient data angle, There is sufficient data to know that there would be some tonnage of force applied to an airliner striking a bird at say 300 mph, So what would be the consequences of striking something considerably more massive than a bird? My estimate is that the airliner would experience a >100 g jolt and that would be rather serious, however I wanted to run it by some other people to double check my work. are there any serious academics on the interwebz?
Not enough information to determine span of time, at least based on the physics I know (Physics 101 and 102). Inelastic collision--based on perfect conditions--no friction, no other loss of energy, etc. m1 mass of first object, 100,000kg v1 velocity of first object, 240 m/s m2 mass of second object v2 velocity of second object v, final velocity combined v=(m1v1+m2v2)/(m1+m2)= (100,000kgx240 m/s + 2000kgx0m/s)/(100,000kg +2000kg)=(24,000,000kgxm/s + 0)/(102,000kg)=(24,000,000kgxm/s)/(102,000kg)=235.29 m/s would be the final velocity for both objects moving together.
Assuming ideal conditions (no friction, etc.), you can calculate the new velocity of the system--which will be about 235 m/s.
There are too many unknown variables to calculate--composition of objects, etc. Also, the main damage to a plane by a projectile is the result of the parts of the plane that are destroyed.
Given the example of an aircraft, the wing mounted jet engines would experience >100 X their mass as stress upon the mounts and guaranteed for certain rip away in <35 milliseconds, and the engines would rotate / tumble as they disconnected. anybody have any alternate theory?
Wouldn't those assumptions make the collision elastic? The OP specifically asked about an inelastic collision.
The amount of force experienced in any collision is proportional to the mass of the other object. While I don't doubt that the bird would see > 100g in such a situation, obliterating it immediately, the aircraft would barely even notice it. US Airways Flight 1549 was going around 200 mph when it struck several birds before ditching in the Hudson River back in 2009. And while it cause both engines to fail, there was very little force ( < 9g) applied to the airframe. http://www.exosphere3d.com/pubwww/pages/project_gallery/cactus_1549_hudson_river.html
No, that was inelastic. Think about a bullet hitting a ball, without friction. That's inelastic. In an elastic collision we have to assume that each part goes a different direction, and it gets much more complicated. Here are the equations I used. http://hyperphysics.phy-astr.gsu.edu/hbase/inecol.html#c1
My bad. I though by keeping kinetic energy constant you were making it elastic as opposed to an extremely inelastic collision. Still, without more data, calculating things like g-forces or acceleration time is not possible.
There is a computer simulation of an aircraft striking the tower at MIT I believe. Basically an airliner would shred like paper in a shredder. Steal also deforms due to the forces applied.
Elastic or inelastic collision, we are talking about having to displace no less that 3 tons of mass how is that done in a seriously short time without catastrophic effects upon the aircraft?
The solid object compresses, and depending upon the composition of the "solid object" the is movement or not, also dependent on the force applied. however, relative to the force applied, the laws of physics will remain in force. that is there will be equal and opposite re-action to said forces. are we in sync here?
BTW: there is NO computer simulation of any of the events of 9/11/2001 where the source data has been published and without any sort of foundation, the cartoons produced by these "simulations" are totally useless.
Solids are generally defined by the property of incompressibility, meaning they don't compress when force is applied to them. Yes, if you apply enough force, the solid eventually yields, but for standard aircraft aluminum that occurs at around 25 tons per square inch, not 3 tons over the whole aircraft.
6160 aluminum used in aircraft has a maximum tensile strength no more than 120 MPa (18,000 psi), and maximum yield strength no more than 55 MPa (8,000 psi). That does not include deformation of sheets once the structure is compromised. Doing a simple mass calculation based in weight and speed, the aircraft would have imparted about 68.5 thousand tons upon impact.
I was using numbers for 2024-T3 aluminum which has a maximum tensile strength around 60 MPa and a maximum yield strength around 40 MPa. Then there is 6061-T6 which gets around 290 MPa ultimate and 240 MPa yield. Either way you go, 3 tons of pressure from displacing air is nothing.
You can guess all you want but proper simulations publish the source data so that the simulation can be verified as being proper, Who is to say that the parameters that were set up in producing the famous simulation cartoons were correct in regards to the strength of the steel in the tower wall and the failure modes displayed by the aluminum aircraft? Real physics takes into account the energy required to perform a given action like that of having to move tons of mass in order to make penetration into the tower.
