Fall Definition and 903 Threads

Let me set the stage for a thought experiment. 1. A physicist in an elevator at some arbitrary height above Earth holding an accelerometer oriented in a direction pointing toward the center of the Earth. 2. No atmospheric drag. Drop the elevator car and make a measurement. The...

I switched majors after my third year to physics. As a result, I have an unordinary schedule. I will be graduating either in summer of 2015 or fall of 2015. I haven't taken the GREs yet, and I am not planning on taking them this coming fall since I am doubling up on physics courses and don't...

Homework Statement Hi, I am doing a theoretical investigation which will be compared to an experimental I'll do later. I am trying to calculate how much time will it take an object to fall a heigh H. the object is a 5x5x5 cm cube. I have the Reynolds number as this Re=3546*Velocity; and I...

Homework Statement A marble is accelerated to a horizontal velocity of 0.50 m/s by rolling it down a small ramp. The marble rolls off the table, which is 0.78 m high. As it falls, it hits a barrier on the way down. If the barrier is 0.15 m from the edge of the table, at what height from the...

Homework Statement A coconut, with ##m = 2.30 kg##, falls from rest from a tree which is ##h = 35.0 m## high. Take ##g = 9.78 m/s^2##. 1. What speed does the coconut hit the ground? Ignore air resistance. 2. If it actually hits the ground with a speed of ##23.9 m/s##, how much work was...

Hey everyone... I have a question about free fall and acceleration. I recently had a question on an exam that went something like this. "A ball is thrown directly up from a building 59.4 meters high. It barely misses the building on its way down and hits the ground 4 seconds after being...

[EDITED. Thanks to Doc Al, Tanya Sharma and dauto] Homework Statement A ball is dropped from rest from the top of a building of height h. At the same instant, a second ball is projected vertically upward from ground level, such that it has zero speed when it reaches the top of the building...

How long would it take for an apple to fall to the Earth if it were as far away as the Moon and how do you calculate that? And, say the apple appeared out of nowhere stationary (relative to the Sun) at that distance, would the movement of the Earth leave the apple behind or would the apple...

OK so let me apologies if I don't seem to fully understand the concept of free fall and am making a far fetched connection. I've been recently reviewing some of my old course material such as vector calculations, Newtonian mechanics,etc, and while reading up on basic vector calculation the...

I'm sorry I'm sure this question is basic, but hours later I'm still stumped. Any hints appreciated. Also I'm trying to work on thinking about the theory behind the solution, so if anyone can include the physics "why it works" behind their hint that would be greatly appreciated :) Homework...

I'm just wonder what would happen for a physics project. I have looked everywhere and can't find anything helpful on the internet. Theoretically, I just need to find what would happen to a large humanoid object reaching a terminal velocity of 100-125 mph and falling down around 4km into said...

EDIT: This is in the wrong section isn't it? How do I move it to the General Physics section? (My bad.) This isn't a homework problem (I'm not in a physics class) so hopefully this isn't the wrong section. My question is about finding the minimum velocity needed for an object (directly...

This question is from Resnick, Halliday, Krane; Physics 5th edition. This is not actually a homework problem rather a question and so I hope it's not inappropriate to post it here. If m is a light stone and M is a heavy one, according to Aristotle M should fall fall faster than m. Galileo...

Hello there, This is my first post on here, so I hope that I've posted in the appropriate sub-forum. My question might seem simple to some, but I haven't been able to find a satisfactory / understandable answer to this question. Thanks in advance for taking the time to respond.

A parachutist's fall is due to gravity of the Earth which pulls down the weight of the parachutist towards it. Initially there is no air resistance. The air resistance increases and acts against gravity. There is a phase the velocity is constant. When parachute opens, air resistance increases...

Hi guys, I have a question that has been intriguing me for some time. If i drop an object 100m at the speed of gravity (9.8), which has a mass of 1000kg - given the initial velocity of zero, i get the following results: velocity = 44.3 m/s Kinetic energy = 980000 Joules If my...

I'm 19, aspiring to go into professional physics, most probably in the astrophysics branch. I'm mostly attracted to gravity (please do not mind the pun), quantum mechanics, string theory, the remote possibility of FTL travel using Alcubierre Drives (or better technology, someday), fusion, et al...

I am well aware that objects of varying masses, shapes, and surface areas will fall at different speeds and accelerations in an environment with a gas in the way such as air due to air resistance. Why is it though, that gravity causes all objects to fall with the same acceleration in a vacuum...

If we neglect the effects of air resistance, the impact speed of a body of mass m released from rest at an altitude of 2 x 10^8 m above the surface of Earth (mass of Earth = M = 5.99 x 10^24 kg, radius of Earth = 6.37 x 10^6 m) It's a multiple choice and I think I have it, but I just want to...

How is electromagnetism different from gravity in that accelerated objects radiate EM waves when accelerated in an electric field but no gravitational waves are generated when objects are accelerated in a gravity field? Why do not planets orbiting the sun generate gravitational waves and...

Homework Statement If a body travels half its total path in the last 1.70 s of its fall from rest, find the total time of its fall (in seconds). Homework Equations Vf=Vi+at Xf-Xi=Vit+1/2at^2 The Attempt at a Solution Well I can see what's going in in the problem (I think). I know...

Homework Statement Your friend makes a wager with you. He holds a $50 bill between your thumb and finger, and says you can keep the $100 bill if you can catch it when it drops. The bill is 16cm long. Using your reaction time do you catch the bill? Homework Equations The Attempt...

Homework Statement In the final second of its free fall, an object covers half the height of its total fall. From what height did it fall? 2. The attempt at a solution I know that the velocity and acceleration at the final second must be enough for the object to cover half the height...

Hi there Just wondering: all objects fall at the same speed, right(not taking into account air resistance)? So if I dropped a feather and a bowling ball on the moon, they'd fall at the same speed. So far so good. But my physics book's definition of weight is "The weight of an object is the...

Homework Statement The Attempt at a Solution The reference to exercise 1.7 is not essential. The only part exercise 1.7 that is relevant to this exercise is the following: if a long narrow tube is drilled between antipodal points on a sphere of uniform mass density and two identical...

Here's the best of my understanding of the official explanation of what happens when O' fall in a black hole. eternal black hole For an outside observer O, O' slow down more and more as you approach the event horizon, at the event horizon time seems to completely stop. In the reference frame...

Homework Statement A boy is on top of a 12 m tall building. He throws a water balloon horizontally, releasing it at a height of 1 m above the top of the building. The water balloon is thrown at 30 mi/h and is aimed at the balconies of an apartment building across the street, 18 m away...

Homework Statement Given data: Tom throws a stone from a cliff 20m above the water, the initial velocity is 9m/s. Calculate the time it takes for the rock to fall down. Homework Equations Now, to my questions. I solved this using the equation: y = - 1/2 gt^2 But, I found myself...

My textbook source is: Fundamentals of Physics, 6th edition, by Halliday, Resnick, Walker According to Newton's well known 2nd Law of Motion: Fnet = ma In chapter 2, in the case of free fall, the Fgrav = mg, where g = -9.8 m/s2, assuming that movement along the axis of y is positive...

Yoyo Problem:( Question: A cylindrical yoyo of mass m and radius R falls a height h from rest. What is its velocity after this fall? My attempt: I drew a diagram and at rest determined that T-mg=ma Where T is tension and acceleration is centripetal acceleration v^2/r So v= sqrt of T-gR...

I know that for short distances from the Earth's surface, x=-1/2gt^2+vt+x works fine for finding the time it takes for an object to fall a certain distance ignoring air resistance. However, what if the distance is many times the Earth's radius? The only thing I can think of to start solving...

Dear members, My name is Gilberto F. A. and I would like to ask your help regarding a topic in Gravitation. I have formal education in engineering and recently, as part of an attempt to refresh my knowledge of physics I started to study again on my spare time whenever I can. A few days ago...

I was having a few problems with Negative gravitational potential energy, I wasn't able to put my finger on why because it worked so well with everything else I had learned. I tried to say it made sense because in space you don't free fall, but that's not actually true, though the...

Homework Statement The original question is: A ball is shot horizontally off the edge of a cliff 35 m high. The ball lands 20 m from the base of the cliff. a. How long was the ball in the air? b. What was the initial velocity of the ball? Homework Equations I believe these would be helpful...

Two very simple questions, but ironically I've listened to a number of podcasts and articles that leave me confused as they don't always sound consistent so... 1. Is a satellite that orbits a planet (i.e. a satellite in free fall) feel the GR effects of the gravity of the planet? In other...

hello, I am new to this forum (so bear with me) I've got a lamp on the ceiling of my kitchen, its got a particular setup that Ill try to reproduce ceiling--------------------------------------------------------- -----------------hook------------------------hook--------...

Homework Statement Hi, I have this assignment that is killing me trying to figure out. I'm in grade 11 physics. Basically, the teacher will be dropping an object at a certain height (We do not know yet). The object will be attacked to the place where it was dropped with elastic bands. We...

Homework Statement A ball A is dropped from the top of a building of height h and simultaneously a ball B is thrown upwards and both balls collide. After the collision the ball A has the double the velocity of ball B Determine the fraction of the building where the balls collide...

if we throw upward a ball with speed x. What can we say about it when the ball returns in the presence of air resistance? What about in the absence?

Homework Statement monkey is a building 79.3 meters tall. as he was free falling, he was shot by a suspect with a dart. which suspect hit the monkey? Suspect a - on a building 65.2 tall, 81meters away from monkey (building to building horizontally), at velocity 55, at angle 10...

Homework Statement A monkey is free falling at a building at height 79.3 Meters. At the same time a dude shoots a dart from a building 65.2 meters tall, 81.0 meters away from monkey building, 55 m/s speed, angle at 10 degree. Homework Equations two dimension kinematics The Attempt...

3 paper dots fall from a 3-hole punch. what is the probability they will land forming a perfect equilateral triangle on the floor x-y plane? Assume the dots are point source singularities, real dots take up space. don't grid the floor because that will constrict rotations. I don't think...

Free Fall simple question, Answer check ASAP please! Homework Statement A flying squirrel falls from the top of a tree, without initial velocity. It travels the last 2 meters of its fall in 0.2s. What was the height of the tree?Homework Equations d=\upsilon_{i}t + \frac{1}{2}at^{2}...

Einstein said one his happiest realizations was that a person in free fall would feel no weight. Unless I am mistaken he said this. But didn't Newton realize this?

Homework Statement A tennis ball is thrown upward with and reaches height of 18 m. What maximum height can reach this ball on the where acceleration of free fall is 6 times less than g? In both cases initial velocity is same. [sic] (excuse my physics teacher's grammar, don't shoot the...

Galileo found in his experiment that all objects regardless of its mass take same time to fall from above, if the air resistance is effectively overcome. Aren't objects with larger mass supposed to fall quickly, since objects with larger mass attract the Earth more strongly than smaller...

Rusty on the math... I am working on a problem and need the derivation of a free fall trajectory for an object at a distance above Earth where the change in acceleration is not negligible. How do I integrate the distance/ acceleration formula taking into account the change in g to get the...

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...