Free fall Definition and 479 Threads

Can an observer, freely falling into a black hole observe another black hole, falling with him, after crossing horizon? I assume one should be, as for freely falling observer nothing special happens, when he crosses horizon. But just wanted to double-check.

1.Small ball with mass m falls from hight h. Find how velocity, acceleration and height depend on time. Air resistance is linear and depends on velocity ##F = kv##. 2. Air resistance ##F=kv## where ##k## is constant. 3. I do not know where to go after ##ma = mg - kv ##.

1.If i were to jump of of Mt. Everest (29,090 ft), how long will it take me to hit the ground? The initial velocity is 0, the pull of gravity is equal to 9.81m/s^2(acceleration). I got 42 seconds, but i didnt calculate terminal velocity so I am pretty sure my answer is wrong to calculate time...

Here is an unsettling question from a practice set that I've been working on today. Unsettling because the answer key contradicts my answer so I need a second thought. A pingpong ball and a golf ball are dropped in a vacuum chamber from the same height and at the same time. When they have...

There is a situation that a bucket which is full of water and has a hole at the side is let to fall freely. Will the water flow out of the bucket? And if it does, will its path be parabolic or linear? Assume that there is no air and hydrodynamics is working. Full detailed answer would be...

Our test group had some issues with an ASTM foam cushion drop test, and I was asked to investigate. I fixed the problem, but noticed something in a high speed video. A 50 kg mass on the hinged platform separates from the platform when the raised end of the platform is dropped. I thought the...

Homework Statement Hello everyone, first time poster. I am in an Analytical Mechanics class and we are covering Dimensionless Form and Free Fall and am struggling with some of the concepts. The question has multiple parts, but looks like this. The equation for a damped harmonic oscillator is...

Homework Statement While standing on a bridge 18.3 m above the ground, you drop a stone from rest. When the stone has fallen 2.50 m, you throw a second stone straight down. What initial velocity must you give the second stone if they are both to reach the ground at the same instant? Take the...

Let's say that I have a stick with weight evenly distributed throughout. I attach a fan to one end of the stick, then balance it from its new centre of mass. I measure the distance from the ground to the stick then drop it. The stick tilts up towards the side generating more air resistance (fan...

Homework Statement An object falls from rest off a building, with a constant acceleration of 9.8 m/sec^2. The object travels half the building in its last 1 secs of its fall before hitting the ground. What is the height of the building? v_0 = 0 a = 9.8 Homework Equations x = x_0 + v_0 t +...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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?

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...