Falling Definition and 1000 Threads

Homework Statement The free fall acceleration of a mass ##m## above the Earth's surface in one dimension can be represented by ##m\ddot{y}=-\frac{mMG}{y^2}## where ##M## is the mass of the Earth and ##G## is the gravitational constant. With ##\dot{y}(t=0)=0## and ##y(t=0)=y_0##.. (1) Find an...

I refer to the time coordinate of an outside observer (ideally hoovering over the BH at large constant distance). Can (s)he actually see something falling into the hole within finite time, that means actually disappearing and making the Event horizon larger? If no, all the merging of black...

According to the holographic principle, It is proposed that the entire information that is kept in a 3D volume of the black hole can be represented in a 2D surface of its horizon. What if we have a drunk falling into a black hole and moves in a random walk in his inertial frame. According to the...

I want to drop a rocket-shaped object from a near-space balloon, with the aim of maintaining a downward acceleration that leaves it's contents in microgravity. I think that this means: The (unpowered) rocket needs to maintain as close to 9.8m/s2 acceleration in order to balance out the...

Can anyone answer this question: In the context of GR, If two objects are in collinear free fall, far enough apart so that the field intensity differs for each object, and one measures the relative velocity between the objects in the coordinate system of the objects using (say) a radar system...

Homework Statement "A hot-air balloon is ascending at the rate of 12 m/s and is 80 m above the ground when a package is dropped over the side. (a) How long does the package take to reach the ground? (b) With what speed does it hit the ground?" Homework Equations ##v_B=12\frac{m}{s}##...

I'm currently in High School and we have to create an idea to make the world better. Mine is to use the force of gravity and convert it to energy to power a system that will filter air. This is supposed to be used in developing countries where there are large amounts of biomass and harmful...

Example problem from a Classical Mechanics book. Find the displacement and velocity of a particle undergoing vertical motion in a medium having a retarding force proportional to the velocity. F = m(dv/dt) = -mg-kmv dv/(kv + g) = -dt (1/k)ln(kv + g) = -t + c kv + g = e^(-kt+kc) v =...

Alright so I've learned that in a vacuum two objects, irrespective of mass, fall at the same speed. This however doesn't make since to me, because I've also learned that on the moon objects fall at a different speed then on Earth due to the gravitational pull. This seems to imply that the...

Hi, it's my first post. When a golf ball and a bowling ball get dropped from the same height. They will both hit the same hit the ground at the same time. But when you drop a ball with radius R and another ball eith radius 2R inside a cylinder with oil then the ball with the biggest radius...

In the spirit of Einsteins happiest moment, I'm working on a new theory of gravity and would like to test a prediction of mine against the experts here at PF. We know that Bob standing on top of the empire state building close to Earth's gravity is aging slower than Major Tom floating out at...

Homework Statement This is not exactly a homework problem. I am trying to review material so that I can tutor it this semester. In the falling film problem, as described in this link: http://www.syvum.com/cgi/online/serve.cgi/eng/fluid/fluid204.html, I am confused why the velocity profile does...

If you haven't seen this video before then go watch it :D Question: Answer: It is pretty hard to imagine it as a spring and here is why: 1) At (o) the spring should move by its inertia not by any force. If we look at the planet we can summarize that there are 2 points (As I think) that could...

when a motorbike makes a turn to the left, it can lean quite a bit to the left without falling down. also its impossible to maintain balance when its on rest, but the faster it moves the easier it's to balance. why?

Homework Statement Consider a massless rod of length $L$ with a small mass $m1$ attached on one end, and $m2$ attached on the other end. The rod is initially in the vertical position at rest on a frictionless surface, with $m1$ on bottom and $m2$ on top. A small impulse is applied to the top...

Hi! I am struggling with this problem the last two days and I cannot decide which solution is correct. Homework Statement A cylinder of radius R is fixed horizontally on the floor. A uniform chain of mass M and length L (L<πR/2) is placed on the cylinder in such a way that one end of the...

So for an outside observer it appears someone falling into is slowing down and then gets redder and redder. But what about for the local observer? From the perspective of the person falling I would imagine that the universe would appear to speed up tremendously. Is it possible you could survive...

I know there are many threads about falling into black holes and I'm sorry for posting another one. I have a specific question and couldn't find the answer in prior threads, although it's possible that it's there somewhere. If A is outside the supermassive black hole and B falls into it, I know...

if I throw a ball of iron on the ocean, the velocity in which it will sink will be lower at the beginning and higher getting near the deepest part of it? As it may be forced by the pressure of water? (the weight of water)

If an object is an infinite distance from a black hole and falls directly to the black hole without being affected by any other force, what is its velocity at the event horizon?

Does an object falling into the sun reach approximately the speed of light?

Homework Statement A limp rope with a mass of 2.4 kg and a length of 1.3 m is hung, initially at rest, on a frictionless peg that has a negligible radius, as shown in the Figure. y1 is equal to 0.44 m. What is the vertical velocity of the rope just as the end slides off the peg? Homework...

An unfortunate incident happened at our triple effect caustic evaporator (32w.t% to 51w.t%). The third effect (highlighted red) where major steam (~12-13bar depending on flowrate) assisted evaporation take place, here for some reason Ni tubes get severely collapsed, while the plant was offline...

G'day Guys and Gals, I'm working on trying to come up with a best-fit excel sheet for work. Basically I'm trying to find out where dirt/rocks will peak if dropped down a pipe at any given angle. As attached, my crude diagram - I'm trying to calculate the blue line. The height of the container...

1. What have I done wrong when I set this GCSE question?! (shortened) Gravity: 10 N/kg Bowling ball: weight 10 N, air resistance 0.05 N, overall force 9.95 N Football: mass 0.5 kg, air resistance 0.05 N Students need to work out: effective force on the football (4.95 N) bowling ball (a = F/m =...

If we have an infalling observer through the event horizon,will she see the end of the Universe?

Homework Statement The statement of the question is:A chain of uniform linear mass density ##\rho##, length ##b## and mass ##M## hands as shown in the figure below. At time t=0, the ends A and B are adjacent, but end B is released. Find the tension in the chain at point A after end B has...

I was watching a video about how an observer outside a black hole would watch someone slow to a halt at the event horizon and I don't question it, as that makes sense. My first question to the Astrophysicists out there is what the observer falling into the black hole would see. It would make...

Hi I'm trying to explain how this cartoon is physically impossible I know its impossible from common sense, but i don't know how to explain it using physics terms So my questions are: 1) Does the air resistance force have to be much greater than the Fgrav to make you land safetly? If so...

Homework Statement An airplane flies horizontally with a speed of 300m/s at an altitude of 300m. Assume the ground is level. At what horizontal distance from a target must the pilot release a bomb as to hit the target? Answer: 2.7km Homework Equations a=v/t=d/t2 r_f = r_i + v_i*t + 1/2at2...

Homework Statement Two small bar magnets X and Y are released from rest at the same height above the ground. X falls directly to the ground, but Y passes through a metal right which is fixed with its plane horizontal. Does X reach the ground: (A) at the same time as Y, (B) before Y, (C) after...

Homework Statement Hi! I would need a little help with the following problem: We have found a new planet with density ρ and radius R, and drill a hole to its center. Then accidentally, one person falls into the hole. What is his velocity when reaching the bottom (the center of the planet)...

Homework Statement Suppose you drop a feather and a steel ball of equal masses (0.014 kg) at the same time from a height of 2.2 m and you are told that the feather hits the floor 3.5 s after the steel ball. Estimate the value of the terminal velocity of the feather in air. Then, estimate the...

This is my very first post, so here it goes. I've had this idea for a while but this is my first attempt at putting it into words. We've all heard of the hypothetical demonstration that tries to put gravity into perspective by pitting a fired bullet against a simple falling bullet. The idea...

Homework Statement An asteroid is knocked out of the Kuiper belt and starts to fall toward the sun. (Assume it's initial potential energy and kinetic energy is 0.) a. Write down the differential equation for r(t) giving the position of the asteroid as a function of time. b. Solve the...

Homework Statement Problem states : A student walks off the top of the CN Tower in Toronto, which has height h and falls freely. His initial velocity is zero. The Rocketeer arrives at the scene a time of t later and dives off the top of the tower to save the student. The Rocketeer leaves the...

Hi guys! So I have been learning about jerk/jolt as the third time derivative of distance, and thinking about Newtons law of universal gravitation, and I have come to the conclusion that a falling object must have jerk, and even jounce. Here's how I came to that conclusion: The acceleration of a...

Homework Statement https://physicsforums-bernhardtmediall.netdna-ssl.com/data/attachments/72/72755-bc8e4b32405460abcfa2d8e4880f7037.jpg I'm trying to figure out the terminal velocity of the loop as it falls through the magnetic field (figure 7.20). 3. The Attempt at a Solution The...

If I were to drop a sphere down a tube of fluid. What are the effects of the wall of the tube on the sphere? Assuming the sphere has an extremely low Reynolds number of less than 1. Is it right to say that the ratio of the radius of the tube and the radius of the sphere has an effect on the...

So if you have an object in a hot air balloon that it traveling upwards at constant velocity, and this object falls out of the hot air balloon, is its initial velocity 0 or is it the same as that of the balloon? Thanks in advance!

Homework Statement A Red Cross airplane is traveling horizontally east at velocity v_0 = 80.0 m/s and height h = 350 m above the ground. The plane carries emergency supplies for a village inaccessible by road. The plane will drop the package (without a parachute) into a pile of soft hay...

Homework Statement 1. (30 points) A very flexible uniform chain of mass M and length L consisting of very small links is suspended from one end so that it hangs vertically, the lower end just touching the surface of a table. The upper end is suddenly released so that the chain falls onto the...

Homework Statement Suppose a hollow metal shell (outer radius 25.3 cm, inner radius 5.2 cm) carries charge Q = -7.99 pC. There is a tiny hole in the sphere, so small that it does not affect the charge distribution or the electric field created by the charge. An proton is released from rest at...

I had a little thought experiment, in which there are two objects with the same masses near each other (same height) on freefall. If I set up a point that is on an instant besides the two masses and call it the center of torque, I get that the torque produced by the nearest one's weight is...

You have a piano that you have just pushed to the top of the 3m long ramp that goes into the truck. The ramp is at a 20-degree angle. You think your friend has a grip on it and she think you do when you all let go. How long do you have before the piano gets to the bottom of the ramp? Assume...

Have to make a table of measurements, height-time-velocity-acceleration, taken from a free falling object and my professor asked for the acceleration of each trial which is leaving me very confused because I thought g = 9.8ms2 is constant. So I'm going to have to write a bunch of 9.8s or is...

Hey all, question about gravitational potential energy. If an object begins on ground then gains height when it falls then energy it consumes to fall down was the potential created by moving upwards, if an object was created in space, then moves gravitationally towards a celestial body where...

Consider the famous kinematics equations $$x_f=x_i+v_i\cdot t+\frac12at^2$$ My question is: does this equation work for every point A & B along the parabola formed when dropping an object?

Homework Statement The disk of mass m and radius R is at position (a), upwards. it is free to rotate round point O on it's circumference. If falls and reaches state (b), horizontal position. What are the velocities and accelerations in position (b) Homework Equations Moment of inertia of a...

I have seen youtube videos where two balls of the same size and of different masses are dropped from the same height and they hit the ground at the same time. I understand why this is so: the increase in the mass of a body increases the force of gravity acting on the body, but also decreases...