Fall Definition and 921 Threads

I ask because as you might have heard recently a person fell out of a roller coaster when her restraint came open last week in Ohio. I was always told that the physics of these ride designs made it so that the people would be safe even without a restraint. I'm skeptical about a few things...

Fall Schedule 2013, URGENT HELP Hello all, I am new to the Physics forum (hence if this post is in the wrong place, you know why). My current dilemma is my schedule for this Fall, I go to a mid-sized state university with a small Physic department. My school does not offer PhD or even a...

So the way my schedule is looking, I will be finished after a fall semester. Now I want to do an REU during that summer leading into the fall, so I won't really be studying then, which is from what I understand, when most people do their studying for the PGRE. Would it be best to postpone my...

Just wondering, if the way to describe the movement of objects through spacetime is to say that they fall through the curves created in 4D spacetime, then is it a stupid question to ask why objects don't rise through spacetime? Or is this the same thing and rising and falling are one of the same...

I've heard many horror stories. Any tips? Any specific parts of Griffiths I should be extra keen on? Is the answer...*sigh*... "all of it backwards and forwards"?

Homework Statement You place a 2kg box against the side of a cart. Nothing is used to stick the box to the cart which accelerates to the right. The coefficient of static friction is 0.6. Find the minimum acceleration of the cart needed so that the box does not fall Homework Equations...

I'm working on my bachelors in Electrical Engineering and for Fall Semester I'll be taking first semester circuits, linear algebra, and third semester university physics. Can someone recommend another class that would benefit me in electrical engineering. These are the classes I'm looking at...

Homework Statement Given: If a body of a mass m falling from rest under the action of gravity encounters an air resistance proportional to the square of velocity, then the body's velocity t seconds in the fall satisfies v' = g - [(kv^2)/m] where k>0 and is a constant that depends on the...

Homework Statement A student throws a set of keys vertically upward to her sorority sister in a window 4m above. The keys are caught 1.5s later by the sister's outstretched hands. (a) With what initial velocity were the keys thrown? (b) What was the velocity of the keys just before they were...

If I am in orbit around Earth that means that I am in constant free-fall around earth. Is this an inertial reference frame?

big G = G = 6.674E-11 N(m/Kg)^2 Mass of Earth = Me = 5.972E24 Kg Radius of Earth = Rsurface = Rs = 6.371E6 metres THIS IS NOT HOMEWORK Okay so I was interested to know how you would work out the distance you'd need drop an object from (above the Earth's surface), for it to reach a given...

Hello, First post hear so bear with me. I have a mass in free fall with a viscous friction which can be derived from the dissipative potential Kv2/2. I must find the Lagrangian and proove that the maximum speed is v=mg/K. I have the following Lagrangian...

I'm finishing up my freshman year of college and next fall I'm planning to take: Differential Equations and Dynamical Systems (4 credits) Analysis I (4) Waves and Thermal Physics (4) History of Classical Music (for gen. ed. requirements) (3) I'm fairly confident about my course...

Yes, yes I did my homework - I googled this and got many results but none seem to answer my query. I am not a historian so bear with me. I had a picture in my mind that civilizations seem to appear after we discovered agriculture and thereafter each civilization advanced and continued to...

Homework Statement This has a fairly long problem statement, so I'll condense it. There are two gates with 81 vertical pickets and two horizontal support bars. These are holo rectangular tubes. The pickets are 2" x 2" x 3/16" box beams and support bars are 4"x6"x3/16" Box Beams. One...

hi, thanks for taking time to read my first post. i'm trying to solve a little mystery and would like to do so in a methodical and logical way. it is my basic understanding that free-fall acceleration is a constant on Earth of 9.8m/sec2 that if an object is released from a height it...

Like the topic; if you boil proteins (or vitamines for that matter), will the molecular structure break? For example warm milk etc.

Electricity and Magnetism 1-Griffith level Quantum Mechanics-1 Griffith Mathematical Physics II topics are mostly PDE's and complex Analysis And either Solid State physics or intro to Cosmology. Both classes are senior or junior level Do you guys think this is a decent schedule for a...

My adviser has suggested this lineup for me for the fall semester this year. I have not had any problems understanding calculus so far, and I am very excited about physics and statics, but the idea of this kind of workload is new to me and is quite daunting. Is this doable? Or would you advise...

In classical mechanics is defined potential and kinetical energy for particular particle. For example, in case of free fall potential energy of the particle is ##mgh## and kinetic energy is ##\frac{m\upsilon^2}{2}##. In QM there isn't potential of the particle, but potential of part of the...

Say I have a special type of black hole, an infinetly small one. I am standing still in deep space and i let a point mass to fall. What is it's equation of motion? I'm interested in the equation itself not just an explanation. It should be sth like this x=f(t).

Homework Statement I have to make an egg drop device. I was fishing for ideas. It needs to be the fastest time and survive the fall. If I win I get 4 points E.C.. Homework Equations Impulse = Ft Position function for falling object s(t) = -16t^2 +Vo + So s'(t) = -32t F = ma p =...

Homework Statement Rod AB of length 2l, inclined to the horizontal at an angle \phi, falls, without rotating, with some height h on a horizontal table and hits the table surface elastically first left, then right end. During the strike the right end, the rod again consist angle with the...

Just wondering when people would recommend to take the GRE. I'm pretty sure that I won't be applying for pure physics graduate programs (I'll probably do applied physics or a particular subset of physics), but I'll finish the coursework for the grad school track of my school's physics major in...

In high school physics, which I am in, we learn that to find the distance that and object falls can be found with the equation, x=v0t+1/2gt2. We also learn that the force of gravity between two objects can be found by Fg=Gm1m2/r2 and thus acceleration due to gravity can be derived to be g=Gm/r2...

My course options for next fall are: Nonlinear PDEs (probably going to take) the three below are all offered at the same time and date Mathematical physics Evolutionary computations Numerical analysis What should I take? Numerical and evolutionary both count as a numerical methods course. If I...

This is a spin-off of a parallel discussion, starting from: https://www.physicsforums.com/showthread.php?p=4281037#post4281037 The question is what SR predicts that an accelerometer in free-fall will read. This issue may be simply due to different people using a different meaning of "SR", but...

Hi I can understand how once an object is falling in converts PE to KE. My question is how does it move in the first place. I know if we assume a gravitaional force that is fine. However from the perspective of energy it seems if an object starts with no KE it can not lose PE by moving...

Standard Monty Hall Problem: Contrary to what you may be thinking this is the easy one for me to understand. Once it was explained, the 2/3 odds make perfect sense. The trouble comes with the related "Monty Fall" problem: The probabilities quoted for this are 50% win chance whether you stick...

Homework Statement Passengers on the drop, a free fall ride at the fair, sits in cars that are raised to the top of the tower. the cars are released for 2.6 s of free fall. a) how fast are the passengers moving at the end of the free fall phase? -25.506 m/s b) if the cars in which they ride...

In physics class today, our teacher wanted to demonstrate that mass doesn't have an effect on fall speed. (The class was about gravitational potential energy becoming kinetic, mgh = 1/2 *mv^2 and all that) Here was the set up: He had a small rail (two parallel thin metal poles) sloping down...

Assume that I have capillary of radius 0.08 cm. I want to test this capillary for capillary rise action. Formula will be T=hrgρ/2cosθ what will be the rise for water.. ( please tell me the calculated value) And, what will be the fall in mercury. ( How to show it negative as its...

Homework Statement A) Explain what will happen if I drop a spring at equilibrium. B) Explain what will happen if I drop a Hoberman ball. C) Explain what will happen if I drop the spring in a falling elevator (in free fall). Homework Equations T=kx [b]3. The Attempt at a Solution...

On the nature of the "infinite" fall toward the EH Observers Alice and Bob are hovering far above the event horizon of a block hole. Alice stops hovering and enters free fall at time T_0. Bob waits an arbitrary amount of time, T_b, before reversing his hover and chasing (under...

Time for Droplet of Water to Fall .25m from Hole Homework Statement A cylindrical tank .7m tall is filled with water and placed on a stand (below it) that is .3m tall. A hole of radius .001 m in the bottom of tank is opened. Water then flows through the hole and through an opening in...

So in a physics lab, we threw a ball upwards and recorded its acceleration. If you look at the graph there is actually a period of time where it goes from positive acceleration to -9.8 m/s2. But how is that possible? Before I let go of the ball, it experiences a positive acceleration because I...

Let there be an obj. which is made to fall from a certain height in a gravitaitonal field. where a= 10 metre per second squared Say it falls for 1 second. v(final velocity)= 10 metre per second. How much distance does it cover in that 1 second? distance = speed x time = avg...

Hello, I've been doing some relativity self-study and have what may be a silly question but one that has me scratching my head. I understand conceptually that under GR, gravity is not a force but rather the effect of objects following the straightest possible path (a geodesic) over curved...

Homework Statement a. Is the downward acceleration value of gravity in Winnipeg acceptable anywhere on Earth? why or why not? How could you test this theory using common technology (no computers)? b. Does the temperature of air affect the drag on an object? Why or why not? c. When you drive...

Homework Statement Two children stand on a platform at the top of a curving slide next to a backyard swimming pool. At the same moment the smaller child hops off to jump straight down into the pool, the bigger child releases herself at the top of the frictionless slide. During their...

A Person in "Free Fall" Newton's 2nd Law Homework Statement An 80kg aviator is in free fall and acquires a velocity of 60 m/s and then opens his parachute. After falling an additional 30m, his velocity has been reduced to 20 m/s. What is the average acceleration of the aviator while his fall...

Homework Statement Within this lab I was supposed to perform a virtual experiment and find the rate a ball dropped on the moon, mars, and earth. I have recorded all of my results in the table below. My problem is that my average velocity on Earth ended up as 8.9 m/s, and I thought that the...

free fall equations ...Sky diver Felix :) need some help please hi :) OK..i tried to use the equations below to evaluate the distance or the time at which felix will reach the speed of sound ...but i failed ..i need some help: here what i did: first i neglect the air resistance , but the...

This WILL sound sketchy and far-fetched, but read every bit of information carefully, and you will hopefully understand, I know overall the reason why the objects fall together at the same rate is because there is no air-resistance, but working with formulas it shows how some things are...

If you push an air filled ball down to the bottom of a bucket of water an acceleration is caused by the buoyant force being greater than the force of gravity, so you have a net force up. I was wondering if you tried this on the ISS where water becomes a floating sphere. How does the ball...

I have this excerise to do: A boy is standing on the tower o height h. He shot with his slingshot a rock vertically up with velocity v0, gravitational acceleration equals g. After what time t the rock has fallen? Answer is t = (v0 + sqrt((v0)^2 + 2gh))/g but how to get to it...

With the leaves starting to change I have been wondering what causes the more dramatic colors verses the more dull leaf colors. I have been told that sunny days and cool nights is the best environment for good autumn colors. If this is true, why does that create the nice colors? Thanks!

I have always had this question and I have received various answers from angular momentum conservation to gyroscopic effect. But I couldn't really understand the principle. Also, why it becomes easier to balance the cycle when you move the handle?

Homework Statement If an object travels half its total path in the last second of its free fall, from rest, find: (a) the time, and (b) the height of the fall Homework Equations I'm not sure at all what equations to use The Attempt at a Solution The only thing I can think of...