Fall Definition and 921 Threads

Title says all, why clouds are up? have the air more density than water? Thanks!

Homework Statement I want to numerically simulate a fall with air drag. In class, we used these equations to produce a table simulating free fall (using a ti calculator): dt=0.1s a=9.81m/s² tn+1=tn+dt vn+1=vn+a*dt xn+1=xn+vn*dt When I compared that system with the curve produced by the...

Homework Statement A rock thrown straight up climbs for 2.50 s, then falls to the ground. Neglecting air resistance, with what velocity did the rock strike the ground? Homework Equations well we are looking for v=? we have: t=2.50 s and g=9.8 ^do we need gravity? yes, right? =S...

I read about electrons and positrons free fall within a superconducting cylinder, in this book (p 105): https://www.amazon.com/dp/0521675537/?tag=pfamazon01-20 I don't understand what I read. Apparently, electrons would feel an electric field mg/e that would actually freeze them in the...

Homework Statement From the GRE 0177 practice exam: A thin uniform rod of mass M and length L is positioned vertically above an anchored frictionless pivot point, as shown above, and then allowed to fall to the ground. With what speed does the free end of the rod strike the ground? The...

Homework Statement A ball is dropped from rest from the top of a building and strikes the ground with a speed vf. From ground level, a second ball is thrown straight upward at the same instant that the first ball is dropped. The initial speed of the second ball is v0 = vf, the same speed...

Homework Statement A particle falls freely through a distance of 1.00 m starting from rest. Assume resume that g = 10 m/s^2. How much time does it take to fall? (4E-1) Homework Equations I think a=vf-vi/t The Attempt at a Solution I've tried 10m/s^2=1/10m/s-0/t And tried to...

Hello Homework Statement I have this problem, even though it might seem very simple. A boy falls from a distance and lands on a net. When he reaches the net, it de-accelerates him with 4*g. The question is: What amount force does the boy exert the net? The Attempt at a Solution I would say...

Homework Statement Heather and Jerry are standing on a bridge 50\;m above a river. Heather throws a rock straight down with a speed of 20\;m/s. Jerry, at exactly the same instant of time, throws a rock straight up with the same speed. Ignore air resistance. How much time elapses between the...

I've tried finding this in the forums elsewhere, but can't seem to find the answer I'm looking for. So here's my dilemma... There are two objects, object X and object Z, that are the same volume and shape. However, object X has a greater mass than object Z. Objects X and Z are both dropped...

In free fall, there is no air resistance, so the only force acting upon the object of free fall would only be its weight. Now the question is, if an object keeps accelerating due to free fall, wouldn't it eventually reach the speed of light? For example, Earth's g=9.81 m/s^2, so over a course...

Homework Statement A body falls vertically from rest. During the nth second it falls a distance d. Prove that by the end of the nth second it has fallen a total distance (D) of (2d+g)^2/8g Homework Equations x = x0 + V0 + 1/2at^2 where x0 = initial position v0 = initial velocity a...

This is a thread for all us nervous Fall 2009 grad applicants. All my applications are in and all my letters of recommendation were sent in. I don't want to post any stats or profile data until I get my admissions decisions in. Where did you guys apply? What field do you want to pursue...

Homework Statement maria throws an apple vertically upward from a height of 1.3 meters with an initial velocity of 2.4 m/s. A) will the apple reach a friend in a treehouse 5.3 m above ground B)how long will the apple be in the air before it hits the the ground Homework Equations...

1. To determine how high a cliff is, a llama farmer drops a rock, and then 0.800 s later, throws another rock straight down at a velocity of −10.0 m/s. Both rocks land at the same time. How high is the cliff? 2. I know some kinematics equations must be used 3. I am stumped...

I need help with a circuit. I need to run the signal in first image through a circuit that can clean up the exponential rise and fall edges and make it more linear. Can anyone help. http://picasaweb.google.com/davidanthonypitts/SignalWaveforms?authkey=5iLxB--Xdqs#

Homework Statement A man standing on the sidewalk throws a set of keys vertically upward to his wife in the window of their apartment 4.0 m above. The wife catches the keys 1.5 s later. (a) With what initial speed were the keys thrown? (b) What is the velocity of the keys just before they were...

Will oil prices rise in 2009? Or will the economy keep the prices down for a while?

Homework Statement A block of mass 3 kg is hung from a spring, causing it to stretch 6 cm at equilibrium, as shown below. The 3 kg block is then replaced by a 4 kg block, and the new block is released from the position shown below, at which point the spring is unstretched. How far will the 4...

I'm a second year physics major and I'm considering starting a co-op job doing research starting this summer. The outcome of this is that I would end up graduating in the fall, and my plan after school is to get a PhD. Since hardly any PhD programs start in the spring, I'd have a good 9 months...

So for the Autumn picture contest I chosed an awesome view of the Danube valley. Unfortunately the sun wasn't that bright that day. So the choice was scenery versus light. Scenery won, these were the losers:

Free Fall Trajectory So I am basically lost in what that means. I think it is the component method for vectors? Am I right? Some background on the lab: We rolled a marble down a curved ramp so that it went off the table and hit the ground in front of the table. (we marked where it hit with...

Homework Statement Water falls at the rate of 250 g/s from a height of 60 m into a 780 g bucket on a scale (without splashing). If the bucket is originally empty, what does the scale read after 2 s? Homework Equations p=mv F\Deltat=\Deltap The Attempt at a Solution So I assumed that the...

Homework Statement The string in a yo-yo is wound around an axle of radius 0.512 cm. The yo-yo has both rotational and translational motion, like a rolling object, and has mass 0.206 kg and outer radius 1.88 cm. Starting from rest, it rotates and falls a distance of 1.20 m (the length of the...

Homework Statement This isn't really a homework question that I have but more of a question i am trying to find out myself. When objects are near the surface of the earth, objects accelerate at an average of 9.8 meters per second^2. However when we get farther away from the earth, say have...

Homework Statement a ball is thrown straight down from the top of a 220 feet building with an initital velocity of -22ft/s. What is the velocity of the ball after 3 seconds? What is the velocity of the ball after falling 108 feet? Homework Equations s(t) = -16t^2 + Vi(t) + si...

Homework Statement A ball is dropped from 1.5 y(m) and hits the ground in .54 t(s). What is the value of g (m/s^2)? The accepted value of g = 9.8m/s^2 Homework Equations y=1/2gt^2 The Attempt at a Solution I'm getting this wrong, but this is my attempt. 1.5 = 1/2g x .54^2...

Homework Statement A ball is tossed from an upper-story window of a building. The ball is given an initial velocity of 8.20 m/s at an angle of 15.0° below the horizontal. It strikes the ground 3.00 s later. (a) How far horizontally from the base of the building does the ball strike the...

Homework Statement A stone is thrown upward at an angle of 51° above the horizontal. Its maximum height during the trajectory is 26 m. What was the stone's initial speed? m/s Homework Equations a=v2/r v2=vo2+2ax C=2\pir The Attempt at a Solution I figured the acceleration is...

A doctor, preparing to give a patient an injection, squirts a small amount of liquid straight upward from a syringe. If the liquid emerges with a speed of 1.5 m/s how long does it take for it to return to the level of the syringe? what is the maximum height of the liquid above the syringe...

Homework Statement Anthony is going to drive a flat-bed truck up a hill that makes an angle of 10 degrees wtih respect to the horizontal direction. A 36.0-kg package sits in the back of the truck. The coefficient of static friction between the package and the truck bed is 0.380. What is the...

It was such a beautiful day here in southern Ontario Barb and I decided to take a lil drive. We took a few photos on our trip. The Credit river valley is 2 minutes from our place, so we shot the fall colours. There are some beautiful colours right outside our apt. Next we drove to the area of a...

Hello friends, I am very new to this forum and I´d like to consult you if i have any questions. Currently I am studying basic physics for my ug. I´d really apreciate it if you could help me out. Homework Statement A ball is thrown straight up from the edge of the roof of a building. A...

Sometimes Technology makes me happy, and sometimes it makes me cry, and THIS is definitely one of those times that it makes me cry. So we used a free fall program to give us values of the distance, velocity, time and acceleration. Then we had to graph it on Excel, and then find the...

1.what are the the constants of motion of a free fall body(treat this as a one-dimension motion,so there are two [independent] constants of motion )? 2.are they initial velocity and initial displacement？ 3.and i know the total energy(T+V) is one,but they are not independent with the...

It's that time of year again. Or as Bob Dylan would say, "the leaves, they are a-changin'." I just found this cool website with maps of where the leaves are at peak color for parts of the USA. They update twice a week; go to these links and click on "Current _____ report" to get the latest...

Homework Statement 45. A freely falling object requires 1.50 s to travel the last 30.0 m before it hits the ground. From what height above the ground did it fall? Homework Equations x = xi + Vit + (1/2)at2 Vf2 = Vi2 + 2ad The Attempt at a Solution First found the initial...

HELP! PLEASE concepts in free fall an object is thrown upwards, at the top of the path it has a) zero acceleration b) maximum momentum c) maximum kE d) is at equillibrium e)none of the above i know accelarion is 9.8m/s^2 i also know is not KE since at the top is potential im...

The moon's gravity is about one sixth of the Earth's. (Basically, one sixth of 9.80m/s^2). If two objects were dropped at the same height on the Earth and on the Moon, the time it would take for the object to reach the surface of the moon compared to the Earth is... a) 6 b) 36 c) Square root...

From what I understand, from a frame of reference outside a black hole, it takes an infinite amount of time for a test particle to cross the event horizon. But it takes finite time for any black hole to evaporate. It seems there is no horizon left to fall through.

Ok this sucks. This is the second time this year I'm down with a fever and flu. The first time it happened last semester it lasted for 2.5 weeks. I'm just wondering how often you guys fall ill on average annually.

Hi everyone! I have 7 questions here, I completed them all, but I’m not sure if I got them correct. I would greatly appreciate it if someone could have a look at them and let me know if I need to fix anything - I had the most trouble with question 3. Thank you so much for your time! :smile...

A flea jumps straight up to 0.390m. How long does it stay in the air from the time it jumps up to the time it lands? First of all, I found the initial velocity. with the initial velocity, i tried using the equation d = v1t + 1/2at^2 to get the time. but apparently it's wrong...;; How do...

Homework Statement an attacker at the base of a castle wall 3.65 m high throws a rock straight up with the speed 7.40 m/s at a height of 1.55 m above the ground. a.) will the rock reach the top of the wall? b.) if so, what is its speed at the top? if not, what initial speed must it have to...

Hi, Some time back I was saw a discovery documentary, can't remember the name, but in that somewhere they told that under free fall if possible to centre of earth, it will take around 32 Hrs or so.. No calculations or details were given. So I wonder will it take so much time or how...

A freely falling object requires 1.50 s to travel the last 30.0 m before it hits the ground. From what height above the ground did it fall? I have been working on this for a while and seem to be going wrong somewhere. I am unclear as to how free fall is meant here. I know that it need...

I am having trouble with this one. for all the formulas I tried I need the velocity, which they don't tell us in the problem. Any help would be appreciated . A stone falls from rest from the top of a cliff. A second stone is thrown downward from the same height 2.4 s later with an initial...

Homework Statement A wrecking ball is hanging at rest from a crane when suddenly the cable breaks. The time it taktes for the ball to fall halfway to the ground is 1.2s. Find the time it takes for the ball to fall from rest all the way to the ground Homework Equations v=vo + at The...

AP free fall question (solved) Homework Statement I have problem with question b. A hot air bolloon is traveluing vertically upward at a constant speed of 5.00m/s. When it is 21.0m above the ground, a package is released from the balloon. a) for how long after being released is the...

Homework Statement A falling stone takes 0.28s to travel past a window 2.2m tall. From what height above the top of the window did the stone fall? The Attempt at a Solution Vo=?, the velocity at the top of the window a= -9.8m/s^2 t=.28s d=2.2m v=? Vo=(1/2at^2-d)/-t...