Impact Definition and 911 Threads

The US has an extreme string monopoly situation compared with other countries (as several posters including f-h and John Baez have mentioned elsewhere) in the sense that there is only one non-string QG research group in the whole country. This contrasts with Europe, Canada, not to mention...

Hiya, I have had to do an investigation on hookes law as part of my primary school teaching course. i am by far not the best at understanding physics. Can someone please explain to me what effect the width of a piece of elastic has on its elasticity and why? thanks

Testing of Impact Sensor--Verify G-Force Readings I'm thinking either free fall test or pendulum but I was just curious if anyone could suggest an easier method We are looking for a way to test a newly developed impact sensor and verify that we when it says it has been hit with 5 g's for...

Why is more impulse delivered during a collision when bouncing occurs than during one when it doesn't?

[b]1. A mass is hitting the end of a hinged rod. After impact they begin to rotate. The motion is then confined to a single plane. why? what plane? [b]3. I am a bit confused by what they mean by a single plane. Are they saying that there are only x,y coordinates? Is this just a condition for...

I'm still working on the last glacial transition. The other week I drafted this comment: Any questions?

gooooood evening.. i have presentation about the effect of vibration on human and i did not find what i want and i did not understant the topices when i searched from google .. so I will be grateful if anyone could help me..

Hi all I fly model planes in combat and need to build a wing that will withstand a head on impact! I am going to use epp foam to form the wing and a carbon spar the foam will be cut at the spar line and the spar will be a H rotated 90deg so that the foam slots in either side what I need to...

Homework Statement Our homework set today was to find out why is it that when you hit someone at 30mph they have a 20% chance of dying. Yet when you hit someone at 40mph they have a 90% chance of dying. Homework Equations KE = 1/2 M V^2 The Attempt at a Solution First of all i...

A friends father told him that a hydroshock bullet (a type of hollowpoint bullet that spreads out on impact and ussually doesn't exit the target) shot into a mans palm from ten feet away would impart a force on the rest of his body equal to being hit by a semi truck. I know this is ridiculous...

A tennis player swings her 1000 g racket with a speed of 10.00 . She hits a 60 g tennis ball that was approaching her at a speed of 20.0 . The ball rebounds at 40.0 . How fast is her racket moving immediately after the impact? You can ignore the interaction of the racket with her hand for the...

Just a quick question of of curiosity. It's basic physics but I can't remember it :redface: Lets say you have two balls of equal mass about 3 meters up on a ledge. You let one drop straight down, it hits the ground and stops. The other one is pushed forwards with a speed of let's say 1m/s and...

If the moon was to be stopped, what would its velocity be just before hitting the earth? Also, if you could throw in the force of the impact, that would be great too. And another thing, how long would it take?

Can anyone explain to me why Pythagoras' Theorem governs the rate of change, of mass, length and time within accelertated bodies? It's a simple theorem learned by most children by the age of eleven, so one would expect the answer to this question to be quite simple as well.

Homework Statement A gun on the shore (at sea level) fires a shot at a ship which is heading directly toward the gun at a speed of 40 km/h. At the instant of firing, the distance to the ship is 15,000 m. The muzzle velocity of the shot is 700 m/s. Pretend that there is no air resistance...

Heya, I need help answering a question: If i drop an object that weighs 100 pounds from a height of 6 feet what will be the impact in pounds when the object hits the ground (assume that the ground is a hard surface)? Thanks for any help that you guys can provide. edit: I just...

Hi, i am working on a high school project on how various factors (mass, height and sand particle size) affect crater diameter. I am struggling to find a solid hypothesis/ theory on this question. I have found out that the cube of the diameter is proportional to the KE of the ball, but i am...

Got the first part; the second part of the question asks what angle of inclination the bale will strike, given between -180° and 180°. Drawn out, this seems to resemble a right triangle with a 65 m height, 200.4188 m length (initial X velocity = 55 m/s, time of 3.6422 s), and the inverse tangent...

Hi everyone -- I'm brand new here and didn't really know where to post this question. It's just that some friends and I were drinking beer last night and we began to wonder about something. If you were on a stationary (non orbiting) platform 100,000 miles from Earth and you stepped off of it...

I have a question about RMS voltage. I know Vrms is Vpeak/sqrt(2) if the sine wave is centered around 0V, but what if the voltage has a DC offset? Shouldn't this mean the RMS voltage is more?

Galileo's trial, concerning whether the Earth is moving or stationary, is an example of the intense interaction (conflict) between science and religion in the 17th century. Galileo was put into house arrest in 1633 until his death for suggesting that the Earth is moving. Is the interaction...

if all the ice sticking out of the water from only the icebergs were to melt, would the water level go up or down?

How internal reflection affect the performance of the thin film emissive display devices?

I am in the middle of physics debate with someone who has some rather, shall we say, unconventional views regarding classic mechanical physics. It started when he posted that he feels 9/11 was a conspiracy because a section of a building falling does not increase the "load" (as he called it) on...

I just saw Blood Diamond. I don't know how to say this, but I am never going to buy a diamond in my life.

Car tires seem to bounce very well however they are easily unbalanced and tend to tip over very easy. If you were to connect say 2 or 3 similar tires together and then dropped it, it should prevent the tires from tipping over and stop bouncing. This will however make the mass significantly...

What is shear flow? Hat this flow viscosity? .... Thank you

Hello, I am probably going to suffer some embarassment, once I see the answer to my question. Anwyay, I need to calculate the distance needed to create a 5ft-lbs. impact with a 1.18lb. sphere being dropped vertically onto a surface. How would I go about calucating the vertical distance...

Homework Statement On a frictionless table, a glob of clay of mass .48kg strikes a bar of mass .94kg perpendicularly at a point .34m from the center of the bar and sticks to it. 1. If the bar is .90m long and the clay is moving at 8.4 m/s befor estrikning the bar, what is the final speed of...

I need to calculate what percentage increase in impact strength I will get by inserting a 1" OD round tube with .083 wall inside a square 1 3/4" width tube with a .059 wall. Both are mild steel, ERW tubing. Check attached file for diagram. I can find out the tensile strength, if that is...

I have a question relating to astroid collisions with terrestrial planets. I was reading the Venus wiki, and linked to the wiki about colonizing Venus. One method for reducing the massive amounts of CO2 was a big impact on the planet, making the CO2 eject into space (if I remember...

When dropping a metal ball onto a foam mat what is the formula for the impact speed. I know the impact speed, rebound speed, the mass of the ball and time of the ball on the mat. I know: F = m[delta]v ...[delta]t and F = mg , where g= -9.8 N/kg But what is the...

can anyone tell me what the impact parameter represents in a simple scattering of particles?

I had an argument with a friend and fellow engineering student the other day about the properties of water in a high-speed impact. It started when I casually mentioned that water (like the new item from thinkgeek.com that we were discussing) exibits different properties at different impact...

Hi, I'm doing this investigation for school, and i came up with the idea of comparing the effectivenss of different matrials at absorbing impact. I have an idea about using a pendulum, where i release a bob of known mass at known starting height then let it hit the material. Thus, afterwards...

I'm currently finishing my phd in astrophysics and ill be 28.5 yrs old when i do so. I'm now looking for a post-doc job and it seems to be difficult. I've attended top undergraduate and graduate schools but seem to have no offers or call-backs on my applications.I'm being told that younger phd...

Is the only difference between these two impact tests how the specimen is held in position for the test? Charpy holds it like a simply supported beam, and Izod does it as if it was a cantilever?

Hello everyone, I am a senior physics student doing a paper on the pi meson. The only real website I can find with relevant information towards it is on wikipedia. I don't really want to use that as a source because of the credibility issue which arises with wiki. So I was wondering, (even tried...

I'm not sure if I'm posting this thread in the correct category, but I figured i'd give it a shot. If this is posted in the wrong category, i apologise. Some of you are probably familliar with the variable speed of light theory. It's something I just recently stumbled upon, almost by accident...

Next semester I am taking a class called Product Engineering and Manufacturing. It's a one semester course where we work with Dewalt tools. Luckily, we have the same tool as last semester, a cordless impact driver. We have to go through the process of finding something to fix on the impact...

If 1kg piece of steel hits steel surface with speed of 5m/s, how can you calculate the depth of the impact? Let's assume that the steel has 0.345 kN/mm2 material shear strength. Second question is that how much speed is needed to that same steel piece to penetrate 1cm thick steel sheet...

http://www.nrl.navy.mil/Review05/images/05Space(Picone).pdf Greenhouse Effect Could Cause a Space Problem Always focusing on the negative. :rolleyes: Actually, the positive benefit (have to reboost the satellite less often) is limited to only a few satellites, while the increasing...

In humans, what exactly will happen to a young teen if he/she does weed and alcohol? Like will their growth stop such as their sex organs and their height and whatnot, or will their brain stop maturing or what? Which of the propaganda is true?

Hi Basically, I am doing an A level project, in which I am investigating impact craters. I am modeling this by dropping ball bearings into sand, and measuring the depth and width of the resulting crater. However, my results are quite unclear, and I would really appreciate some guidance...

In what ways has the Bush administration damaged the US image abroad; potentially having made the world a more dangerous place? http://www.pbs.org/newshour/bb/middle_east/july-dec06/turkey_11-27.html

I'm supposed to determine if a bunch of materials have a high or low impact strength. I did the hard part and determined that the impact strength for each material, but I don't know a relative scale. What is a high value on the izod impact scale test(it's measured in joules). Any idea?

Hi, two wagons with elastic bumpers colide without any friction. Wagon A has the mass 0.1 kg while wagon B has 0.4 kg. After the collision wagon A has the speed 0.5 meters / second and wagon B lies still. Taken in consideration that the collision was elastic, what velocity does each wagon have...

I am designing a piece of test equipment that will be mounted onto a small rocket for meteorological testing. The people running the rocket side have mandated a series of tests that all test equipment must pass before being fitted. One set of tests are pretty severe shock tests...

anyone help me out, please. can anyone tell me the "problems a cell would encouter if this structure ceased to function"?(what would happen, if Golgi apparatus did not exsist)

Small ice cubes, each of mass 5.30 g, slide down a frictionless ski-jump track in a steady stream, as shown in Figure P6.71. Starting from rest, each cube moves down through a net vertical distance of y = 1.40 m and leaves the bottom end of the track at an angle of 40.0° above the horizontal. At...