Fall Definition and 921 Threads

Hi all, Since the pre-registration time for the Fall semester is approaching i need to make plans as what to take next semester. Specifically, i am planning on taking one or two reading courses since they are not offered via regular curriculum. While it is not for sure that i might be...

Homework Statement Describe the motion of a light bulb falling from the ceiling of a train with a constant acceleration. The train's motion is horizontal with respect to the ground. Describe the motion of the light bulb if you are at rest on the rails. If you are at rest on the train. If...

I'm looking ahead at my fall schedule. I work roughly 20 hours/week, but it looks like that will be cut back to around 12 hours/week. I'm definitely taking Modern Physics II (undergrad QM) and Intermediate Mechanics. I'm considering taking Intro. to PDE with this professor, but honestly I'm a...

Homework Statement 71. A paratrooper fell 370 m after jumping from an aircraft without his parachute opening. He landed in a snowbank, creating a crater 1.1 m deep. Assuming the paratrooper's mass was 80 kg and his terminal velocity was 30 m/s, estimate : a) the work done by the snow in...

I have an MS in physics and did not get into any of the phd programs I applied to. What schools are still accepting applications, and which ones might still have funding for students? I am interested in many areas of physics and my experience is in computation and some nuclear. I have average...

Hello, first post. I hope that someone can help me with this. I will roughly summarize the problem, and what I've done thus far. Homework Statement A lady was in an elevator that free-fell 6 feet and abruptly came to a halt. We had to determine a reasonable best case and a reasonable worst...

I have been employed at the same distributor for about 4 years now and just got word last week we have been bought out. Right after the first of the year our owner announced he was retiring and then almost immediately the due diligence began. We have now went from a small company comprised of...

Suppose a 136 kg manhole cover is launched 50 feet in the air. What is the speed of the manhole cover when it hits the ground on its descent, in m/s and mph? I converted 50 feet to 15.24 meters, but I do not know what equation to use here. I understand that acceleration due to gravity is...

Figure 2-42 shows a simple device for measuring your reaction time. It consists of a cardboard strip marked with a scale and two large dots. A friend holds the strip vertically, with thumb and forefinger at the dot on the right in Figure 2-42. You then position your thumb and forefinger at the...

Free fall problem, Help!? Homework Statement Hi, I am having trouble figuring out this problem: A ball is thrown directly upward with an initial velocity of 10 m/s. If the ball starts at an initial height of 2.3 m, how long is the ball in the air? Ignore air drag. Homework Equations...

So, the time has come that grad school decisions are coming in. Anybody received any acceptances yet? I have applied to 8 schools for a master's in math and have gotten accepted to two - Miami University of Ohio and Bowling Green State University.

(I apologize in advance if this should have been merged with my other topic. Homework Statement A 1000kg weather rocket is launched straight up. The rocket motor provides a constant acceleration for 16s, then the motor stops. The rocket altitude 20s after launch is 5100m. You can ignore any...

Homework Statement After falling from rest at a height of 29.8 m, a 0.422 kg ball rebounds upward, reaching a height of 21.7 m. If the contact between ball and ground lasted 1.83 ms, what average force was exerted on the ball? Homework Equations Change in momentum (p) = Fnet* Change in...

does electrons fall out when a current carrying wire is cut well i know it doesn't make much sense n also doesn't have ny effect but still does it happen or not ?

Homework Statement You drop a stone into a deep well and hear it hit the bottom 4.00 s later. This is the time it takes for the stone to fall to the bottom of the well, plus the time it takes for the sound of the stone hitting the bottom to reach you. Sound travels about 343 m/s in air. How...

problem: ladder is leaning against the wall. There is friction between ladder and wall - f1 and there is friction between ladder and ground - f2 what is the minimal angle between ladder and ground that ladder doesn't fall down. I though it's easy, but then i realized it's not only about...

The molecular mass of ozone is 48. But the average molecular mass of air on ground is 29... So, doesn't the ozone layer have to fall?

"Accelerated charges radiate." That much-repeated phrase is the extent of my familiarity with radiating charges, though I am trying to bring myself up to speed on the Abraham-Lorentz-Dirac force. Well, in relativity theory gravity is locally equivalent to an accelerating frame. so if we...

I posted this problem in another section, but it seems to have fizzled out and I’m trying to solve it, so resurrected it here hopefully to get somewhere. I’m trying to calculate the impact force of a free falling cylinder of metal under water accounting for the drag. The cylinder is...

Homework Statement [/b] Problem: How much Air Resistance acts on a 100-N bag of nails that falls at its teminal speed? What process do you use to solve this?

projectile motion (URGENT!) Homework Statement A busy waitress slides a plate of apples along a counter to a hungry customer sitting near the end of the counter. The customer is not paying attention, and the plate falls to the ground horizontally at .84m/s. The counter is 1.34m high...

Yes, I know that this is a silly question. Let's assume that an aeroplane is flying 20 kilometers above the ground and its speed is 900 km/h. There is a black hole in the centre of the Earth that is growing and consuming the Earth. The Earth disappears into the black hole, but what does happen...

[b] an elevator car weighing 50,000 N is 27m from the ground. the cable snaps and the elevator goes into free fall. Shock absorbers have been provided, the coil length is 1 m. Assume elevator is able to lock onto the shaft at the point of contact w/ the absorber so that it does not bounce...

Der is 2 rectangle blocks of ice at a temp of -6. One is placed on top of the other. ie they are frozen together and they are not perfectly flush. And object is placed inside the top block. I have 2 calculate when this object hits the ground. My question is will the top block slide off at some...

This is a simple question, and I'm sure it has a trivial answer, but this thought occurred to me just now. How is it that gravity is able to accelerate things at the same rate regardless of its mass, while one definition of mass is the measure of resistance to acceleration? If two objects...

Here is the original question: - Well, the answer that I came up with is, that, since there is no eternal force on the system, the centre of mass cannot be displaced, no matter what. Now, my doubts are regarding this itself. When the ice melts, it turns into water of lesser volume. In the...

Homework Statement How Long Does it Take An Object To Fall 5 m From Rest? (g=10 m/s^2) Homework Equations None The Attempt at a Solution I have no idea.

Ernie is holding a 2 kg ball at rest at the opening (top) of a 10 m deep well. He releases the ball so that it falls into the well. Assume the bottom of the well represents zero potential energy position. Immediately before the ball hits the bottom, the sum of it's kinetic energy and potential...

I'm reading a maths book called Thomas Calculus and in their method for getting the average speed of an object when only the height its dropped from is known is this formula here which they call Galileos law: y = 16t^2 y being the distance traveled after time. What I don't get is where they...

Homework Statement A mass m is placed on the top of a smooth hemisphere of radius a such that theta = pi/2 it is given a very small impulse and as a result begins to slide down one side of the hemisphere under the influence of the gravitational acceleration g. Show that the mass flies off the...

I would appreciate any insight into these questions; I have had a little EM but no general relativity. Maybe general relativity is not involved at all - just EM with an observer in an accelerated frame. 1. Suppose we have two charged particles Q1 and Q2. Q1 is sitting on our lab table. Q2...

Homework Statement An object is launched upwards with a velocity of 25 m/s. At what time (or times) will the object be located twenty meters above the ground? Homework Equations The Attempt at a Solution I started off with the following variable list: Xo=0 Vo=25 X=0 V=0...

Homework Statement A rocket is fired vertically and ascends with a constant vertical acceleration of 20.0 m/s^2 for 2.00 seconds. Its fuel is then used up and it continues as a free object. What is the maximum altitude reached? Homework Equations X=Xo+Vot+(1/2)at^2 V=Vo+at...

Homework Statement A jumbo jet needs to reach a speed of 300 km/hr on a runway for take off. Assuming a constant acceleration and a runway 2 km long, what minimum acceleration from rest is required to get the jet in the air?Homework Equations I tried using the equation: 2a(X-Xo)=V^2+Vo^2 But...

In Cadence we built a CMOS inverter. I made a transient response graph showing the input and output voltage waveforms. We're supposed to measure rise delay and fall delay of the output voltage. How do I do this? I heard from someone else that it's where the graphs cross 1.5V, but I'm still...

1. Homework Statement A package is dropped from a helicopter. Note that both the helicopter and package are traveling upward at 10.0m/s when the package is released. If the package takes 3.5 seconds to hit the ground, how high was the helicopter when the package was released? If the...

Hey guys, I am a freshmen mech engineering student and so far I have been really disappointed in my college performance. I am on an academic scholarship that I need a 3.0+ to keep, which I thought would be no problem at all. However, I don't know what I am doing wrong. I just took a math test...

I've seen this equation in a book once but I can't seem to find a good explanation of how it was derived. \ t_{ff}=\sqrt{\frac{3\pi}{32g\overline{\rho}}}

I recently read an article about Joseph Kittinger which stated that in a skydive, he was subjected to a G force of 22 m/s^2. Disregarding fluid resistance, don't objects in free fall always experience one g?

Some years ago i fell from a height to the ground (around 10 feet), right on my back and stopped breathing for some 10 seconds. A sudden complete cut off. I am curious what stopped the air. Either the windpipe was squashed by the ribcage, or was temporary stifled from the very impact without...

Homework Statement Rachel drops straight off a high dive whose board is 5 meters above the surface of the water. How long does it take Rachel to hit the surface of the water? How fast is Rachel traveling when she hits the surface of the water? Homework Equations The Attempt at a...

Homework Statement A package is dropped from a helicopter. Note that both the helicopter and package are traveling upward at 10.0m/s when the package is released. If the package takes 3.5 seconds to hit the ground, how high was the helicopter when the package was released? If the helicopter's...

Hi everybody, I am trying to find an analytical solution of the equation of a falling particle of mass M in a gravitational field (described by constant K) when the gravity depends on distance, as in Newton classical theory(I simplified in one dimension). The equation could be M*d2 X(t)/ dt2 =...

Homework Statement Figure out the height of the building using free fall formulas and only knowing two times: 3.25 second acceleration, 1.25 seconds decceleration. Find the height.Homework Equations Dy=V0t + 1/2at2 (only one I can think of that applies)The Attempt at a Solution Dy=V0t +...

Homework Statement A sphere with a radius of 4 is dropped into a paraboloid. How far is the bottom point of the sphere from the bottom point of the paraboloid when the sphere stops falling? What is the radius of the largest sphere that will fall all of the way and touch the bottom of the...

Homework Statement If a car rolls gently (v0 = 0) off a vertical cliff, how long does it take it to reach 73 km/h? A helicopter is ascending vertically with a speed of 7.50 m/s. At a height of 110 m above the Earth, a package is dropped from a window. How much time does it take for the...

Homework Statement a stone is dropped into th water fro a bridge 44 m above the water. another stone is thrown vertically 1.0s after the first is dropped. Both stones strike the water at the same time. What is the initial speed of the second stone? Homework Equations x = x0 + vx0t...

So i have two questions i need help answering. its not homework, but its from a previous exam my teacher gave. x0=x knot and v0= v knot Homework Statement a rock dropped from a cliff falls one-third of its total distance to the ground in the last second of its fall. determine the height of...

Homework Statement A flowerpot falls past two meter tall window in ¼ of a second. Homework Equations From what height did the flowerpot fall? The Attempt at a Solution

Nobel Prize to Barack Obama Barack Obama has won the Nobel Prize for 2009. First off, congratulations to USA and President Obama. Secondly, as a Norwegian, I am deeply worried about how this will affect the credibility and status of the Nobel prize as such: While Mr. Obama certainly...