Impact Definition and 911 Threads

Homework Statement A 40kg branch falls 5.5m and lands on a roof. The roof withstood the the impact. Homework Equations If the impact time was 0.4 second calculate the magnitude of the average force exerted on the roof during the impact. The Attempt at a Solution F=ma doesn't seem right...

Lunar Gravity, On the moon, the acceleration due to gravity is $-1.6m/s$ . A stone dropped from a cliff on the moon and hits the surface of the moon $20s$ later. How far did it fall? What is the velocity at impact.? well here I presume since the rock is just dropped that $v_0=1.6m/s$ but the...

Homework Statement The problem is to get the classical turning point as a function of the impact parameter b for the Lennard-Jones potential. Homework Equations The Lennard-Jones potential is given as [itex]V(r)=4\epsilon[(\frac{\sigma}{r})^{12}-(\frac{\sigma}{r})^6][\itex]. The effective...

Hi, I'm having a bit of trouble with the below practice problem from my textbook. The answer given in the back is -9.52 m/s, but there is no explanation. Thanks for any help. Homework Statement Two balls are thrown off of a 7.25 m high building both at an initial speed of 63.5 mph. However...

Homework Statement In class we derived the Schwarzschild interior solution (constant density). Examine the behaviour of non-radial null geodesics in this spacetime.Homework Equations \Phi(r)=ln\left(\frac{3\sqrt{1-\frac{2M}{R}}}{2}-\frac{\sqrt{1-\frac{2Mr^2}{R^3}}}{2}\right)...

Why when got bomb explosion even stand a few ways away,it exploded and the impact can kill a person?

What's the difference between impact speed and terminal velocity? I'm reading a book that gives a shortcut about how to calculate "The speed at impact in the y-direction when falling from rest" and it gives the eguation vt=9.8t.

i had a question PV=nRT is the V the volume of the container or the gas and if it was the container and i had a balloon and i squeezed it decreasing the volume increasing the pressure will that increase the temperature? thank you

Hi Guys, I have been asked to find out at what point a measurement device go out of calibration when dropped and express that in a g as in G force. Its been 15 years since I studied physics (for 3 years), I do rememeber a bit but I need some help.. I have the size and weight (mass) of...

Well, I've never started a political thread on the boards before, nor do I usually get involved in politics because of its persistently unscientific nature, but I feel this topic is of the most profound significance and thus a VERY worthy and eminent discussion. Many in the know would say that...

im new here and found your forum after using google i have a question relateing to a car accident after getting hit by a moped as the insurance company feels that the force could not have caused any damage hopefully someone here can help as it seems a very good forum. my wife was driving her...

Impact ... what? Force or Energy? I have a question, about what to calculate if calculating whether an immovable object (a wall for example) will break or not after an impact of another object into it. What should I calculate, the force of the impact or the kinetic energy of the impacting...

If an asteroid was moving in the opposite direction of the moon, could it slow it down enough when it hit it to cause it to crash into the earth. and vice versa, could it be going the same direction and acceleration it enough to excape the Earth's gravitational pull? If so, about how large would...

Can anyone recommend a device or way I can measure the impact protection qualities of different running shoes? I am a runner and would be interested in doing this myself. I appreciate it!

Homework Statement I am currently conducting an EEI in which I am looking at the effects of increased mass, surface area and air pressure on terminal velocity. In my experiment, I dropped a parachute of 0.36m^2 from a height of 3m with a mass of 0.01kg. My result was that it took 3.036...

Hi All, I'm hoping some of you with more expertise in such matters can help me out with the plausibility of a scenario for a novel I'm working on. I know you guys must get stupid hypothetical questions like this frequently, so if I'm out of line just let me know and I'll just slink back to...

I am doing a simple steel ball drop test on glass to see if the glass passes the standards. We are dropping 1.18 inches (0.535kg) steel ball at the height of 51inches (1.295m). Now, I can calculate final velocity at the impact, but cannot calculate the actual impact force. One of the method...

So I'm trying to figure out a rather amusing problem. A month ago I was doing some work in my attic when I took a wrong step and plunged through my drywall ceiling and fell a straight 20ft to the very bottom of my stairwell landing. I was knocked unconscious instantly and don't remember...

Thought I was done but not the case... Homework Statement Alright so as stated a couple days ago... "projectile is shot from the edge of a cliff 125 m above the ground @ an initial speed of 65 m/s at an angle of 37° with the horizontal from the cliff." ---- As helped earlier I have...

Homework Statement A vehicle falls 20 mm back onto a smooth steel track after going over a bump. It has polyurethane wheels. Young's modulus is known for both wheels and track materials. What is the force exerted by the vehicle onto the track as it lands? Homework Equations F = mdv/dt KE =...

I have a problem that I'm having trouble cracking and was wondering if anybody has any ideas on it. An impact test that we have to do involves swinging a pendulum of weight 50lbs into a rolling easel (for writing on, approximately 6ft high, with casters). The wheels are blocked so the easel...

So I'm supposing a scenario where you have energy transfer into a solid and waves propagating out from the impact point and i want to measure the energy at different distances from the "epicenter" with sensors. the relationships I've been pointed to are basically conservation of energy at the...

Affluence and its effect on society. Does affluence make people lazy and less motivated to strive for excellence in academics ? is there any correlation ? Just want some opinion or articles that i can read.

Homework Statement A cylindrical metal bar of length L hangs by two strings in a horizontal position. The metal bob of a simple pendulum hits one end of this metal bar in a direction perpendicular to the crossection of the bar. Find an expression for the time t of contact during the impact...

Oldest Impact Crater on Earth Discovered http://news.yahoo.com/oldest-impact-crater-earth-discovered-162802443.html The area in Western Greenland has deposits of Ni and Pt. I wonder if it's from the same source as the crater in Sudbury, Ontario, which is considered to be only 2 (+/-) billion...

Is there a way to calculate the impulse force F if the time of collision is unknown? The only formula I know to calculate this force is F*Δt = m*Δv. Is there a formula that perhaps uses plasticity as a variable instead of time or maybe uses the distance an object moves after a collision? Any...

Aim: To understand the physics(equations) behind this problem. On the channel 'Discovery Science',a the show-presenter was testing guns.In one of the tests,he fires the gun at a certain distance from a 'BALLISTIC GELATIN'(just a jelly of high viscosity to simulate swine muscle tissue). The he...

Would anyone know what altitude would be needed within a vacuum in Earth's gravity to create an impact of 4kg using a weight of 70g? Thanks

Hi all 1 ) Direct central impact occurs between a 300N body moving to the right with velocity of 6 m/s and 150 N body moving to the left with velocity of 10 m/s . Find the velocity of each body after impact if the coefficient of restitution is 0.8 . my answer : Given [/color]...

I'm working on building an enclosure for a machine that is to go on display in a foyer. The machine is about 2x1x1.5m and its primary purpose when switched on is to show how dynamic components work together. My considerations include: Cost: Need something relatively cheap Strength:High...

I am designing my own Charpy impact testing machine and I am unsure what would be the best as well as relatively simple and affordable method I can use to accurately measure the angle the pendulum travels after it has broke the sample. I would also appreciate any complex and more expensive ideas...

Homework Statement Two students threw a paper plane towards the bin, hitting a desk at time t=10. The trajectory can be modeled as follows: x=t-2sin(t), y=4-3cos(t) Then there were a few simple questions before: The students are curious about what would have happened to the paper...

i need to work some estimations for this case for an assignment 30mph vehicle hits a bollard with 667kJ bollard height = 1m vehicle hits the bollard at approx height of 0.7m material = mild steel ultimate strength = 400mpa in one case the bollard is 219mm ext diameter with 10mm wall...

Homework Statement A 15000 kg train traveling at 30m/s collides with a 2500 truck with a 90 kg man going at 22m/s in the opposite direction. The time of collision is 1.5 seconds. After collision, both objects are moving in the same direction with a velocity of 22 m/s. What is the size of the...

A friend posed this question to me tonight. If a vehicle hits a stationary object and you know the distance traveled of the object, the weight of the object, the model of the vehicle and that conditions were dry on a tarmac road, is it possible to work out the speed of the vehicle on impact?

Hey Guys, I have a problem I am working on and was wondering if someone could point me in the right direction. The problem: I need to calculate a force to apply to a given area of the front of a vehicle in relaticely small collision / impact with both a stationary and possibly a small...

Is the biggest danger of an asteroid hitting Earth the debris released from the asteroid? Looking at general articles it seems that the global risk arises from the debris released into the atmosphere which would affect climate. What would happen if no debris was released? I mean, if the...

hey guys i need help charpy impact test. i have attached my graph with the results we had. Does this seem correct? from the graph how do i determine the transition temperature T1 for the material where T1 is normally defined as the temperature corresponding to 50% of energy change between the...

Hello I'm tasked to evaluate the roof of a small power station situated beneath a rather high tower in an alpine landscape, by means of FEA. One requirement is that the roof shall endure chunks of ice falling on it. Problem is, I am stumped as how to find the loads. The Eurocode norms I am...

Hello all, I just finished building an expansion cloud chamber this weekend and have started experimenting with it. Everything looks solid (vacuum, seal etc) but I'm curious about the role my electrostatic field, generated from a bug zapper and a circuit, plays in visualizing the ionizing...

Hi all, this is my first post on Physics forums so I apologise in advance if I have posted in the wrong section etc. This is something that I have been trying to figure out for nearly a week now! I have modeled a vehicle in Solidworks, specifically an external roll cage, and hope to conduct a...

I am given a milk carton (the small kind you drink in schools), and need to protect an egg by adding what ever I can inside the milk carton (nothing can be outside it). my teacher will first: 1) Drop it from the ceiling (9ft, 2.7 meters) 2) Drop a 16lb (7kg) bowling ball on it from a...

I'm working on a small design project and need some help remember what equations to use here. Basically, we are creating a hammering device. A compression spring will be loaded, and a block on the end is accelerated into another block. I need to have it hit with a certain impact force so I am...

Homework Statement An engine is suddenly coupled to a rotating drum by a friction clutch. the moment of inertia of the engine is equivalent to a mass of 40kg acting with a radius of gyration of 111mm. the drum has a mass of 10kg and a radius of gyration of 100mm. the initial velocity of the...

Hello everyone, I'm new here. I'm relatively familiar with some astrophysics calculations, but this particular equation is kicking my proverbial butt. I'm currently writing a sci-fi book series and there's an impact that happens on a moon, but I want to be able to realistically calculate what...

Any problem of collision can be solved using four equations: Conservation of momentum and energy, impulsive forces and impact parameter (distance between center of masses of the particle taken perpendicular to velocity). I can solve problems using first three cases. But how to analyse a problem...

The bright spot about being ignorant is you don't realize how complicated a question can be. Original question: Two sledge hammers, one is 10lb with 5.062 sq in striking face. One is 16lb with 8.265 sq in striking face. I was asking for the difference in force between the two. Things...

can anyone tell me how the orifice diameter can affect the vortex forming ? no much info from internet , thanks for help~:smile:

Hi,I want to design a crude pendulum impact device which i can use to measure initial velocities of objects on a frictionless surface. i.e measure energy at the start and end of the pendulums swing, to see how much has been absorbed into the impact. Heres my question about momentum on...

Why isn't the influence of air pressure assimilated in Archimedes law? If an obect is more dense than the fluid, it wil sink. That is clear, but suppose I could lower down de air pressue, so less force that tends to push the object tot the surface. Is there any situation possible of adjusting...