Fall Definition and 921 Threads

There is a random person falling from the sky. He remembers that he has a jetpack. Unfortunately, his jetpack is weak and is only able to provide upward force equivalent to Fg. WILL HE?SHE STAY AFLOAT OR WILL HE?SHE CRASH INTO THE GROUND? What acceleration will he/she hit the ground?

1. Cuboid of height h is made out of material with density ρ=1000kg/m3 and it can endure highest pressure of σ=90kPa.Cuboid is falling from the height H. When the cuboid hits the ground its centre of mass is at the height h/2.Then starts deformation of the body. During the deformation centre of...

Hello everyone. I have this problem: 1. The problem statement, all variables and given/known d I throw stone from height h at an angle α, then at an angle β (so I know h, α, β). I throw it with same velocity v. The stones fall in same distance d. The question is: find the d (distance) and v...

The answer based on the answer key is 3 seconds. I used the quadratic equation to solve for t. My question is how do we know what sign to use when solving for the final value? For this problem, I had to use the negative sign, but I knew that I needed to use the negative sign because I already...

Homework Statement A ball is thrown straight up from the edge of the roof of a building. A second ball is dropped from the roof 1.00s later. You may ignore air resistance. If the height of the building is 20m, what must the initial speed of the first ball be if both are to hit the ground at the...

Hello! Imagine you drop a steel ball of weight x from a variable height y. the ball hits a steel ramp on the ground which is at 45 degree's I would like to know how I could work out how far away the ball will land. I have had a good look around for this however the closest thing I can find...

Hi guys, I know this is a really simple question, but I'm just making sure I have this concept down: Scenario 1. An elevator accelerates down at 9.8m/s^2. Scenario 2. The elevator cable is cut. If someone is inside an elevator, scenarios 1 and 2 would feel exactly the same to them, correct...

http://edition.cnn.com/2017/08/04/health/exorcism-doctor/index.html What are the medical explanations for those who are allegedly possessed? I just read the CNN news above. In our age when our science is nearly complete where it shows our universe is only nuts and bolts and flesh and blood...

I'm trying to find measurements for the weak interaction at various distances. Any suggests for search terms or relevant paper would be appreciated. Thanks, Dan

Homework Statement A stone falls from top of a well, 10 seconds later sound of water splash reaches the top of the well. How deep is the well? g=9.82m/s2, vsound=340m/s , t=10s 2. Homework Equations s=vt , v=a0+at , s=v0t+1/2at2 3. The attempt at a solution I'm stuck. I know the...

Homework Statement Homework EquationsThe Attempt at a Solution A) W.r.t. Earth's frame, After 2s , velocity of bolt = at = 1.2*2 = 2.4 m/s distance traveled = (1/2) 1.2*22 = 2.4 m Let's say that the bolt reaches the floor at time t. Using s = ut + (1/2)at2 2.4 = 2.4t +(1/2)(-9.8) t2...

<Moderator's note: Moved from elsewhere and therefore no template.> I'm trying to calculate the distance of free fall for an object with zero tangential velocity but a given radial velocity at a given height over a given period of time. This calculation cannot assume that g is constant as it...

Why do bodies in free fall change position relative to each other? For instance in a vacuum with no external forces why can an apple fall towards the surface of the earth? If these objects aren't accelerating then are they considered at rest? And in what sense of the term 'rest'. I think I can...

1. Ut will bungee jump from the golden gate bridge. The height that she will jump from is 65 meters. The rope pulls her up 8 meters above the water. If UT's weight is 63 kg, how far will the rubber rope pull her upwards, if there's no loss to friction or air resistance? Homework Equations...

It is recorded that someone has survived a free-fall from an airplane by being lucky enough to land on snow-laden fir trees. My challenge is this: Create a mathematical model which describes the forces at play in order to determine the viability of creating a safe and fun 'thrill-seeker'...

Homework Statement Question attached My method was going to be: set ##r=R## and solve for ##n(R)## set ##r=2GM## and solve for ##n(2GM)## I was then going to integrate proper time ##s## over these values of ##r##: ##\int\limits^{n=cos^{-1}(\frac{4GM}{R}-1)}_{n=cos^{-1}(1)=0} s(n) dn ###...

Homework Statement A.[/B] Someone is walking outside when the temperature of the air is -10°C. The metabolic rate of walking is 140 Cal/m2hr, and the usual muscle efficiency (20%) applies. They are completely covered by clothing with a coefficient of thermal conductivity of 0.36 Cal-cm/m2hr...

If we consider 2 shells in Schwarzschild spacetime their radial proper distance ##d s^2 = \frac{1}{1-\frac{r_s}{r}}d r^2## follows from the metric with ##dt=0## and ##d\Phi=0##. Integrating yields ##\Delta s## as a function of the r-coordinates of the shells. A reference with the formula for...

Homework Statement "A body dropped from the top of a tower covers a distance '7x' in the last second of its journey where 'x' is the distance covered in the first second. How much time does it take to reach the ground ?" Homework Equations ## S = ut - \frac{1}{2}gt^2## The Attempt at a...

Homework Statement "A ball is thrown vertically upward with a speed 'v' from a height 'h' metre above the ground. The time taken for the ball to hit the ground is." Homework Equations ##s = ut + \frac{1}{2}at^2## The Attempt at a Solution...

If you fall down an escalator going up, do you ever stop falling?

I had been informed that for objects in free fall orbit no proper acceleration would be measured. https://www.physicsforums.com/threads/stationary-frames-of-reference.899195/page-2#post-5658771 But I also understood it that for objects in free fall orbit gravity time dilation would be observed...

If mass increases with speed then what is the mass and speed of a particle falling from a large distance into a black hole or onto a neutron star?

Homework Statement When throwing a ball, a student has a friend time how long it takes the ball to reach the maximum height. Before they start the experiment, the friend predicts: “If you throw the ball faster, the ball will reach the highest point in less time.” Do you agree or disagree with...

Earth will not fall into sun because it has inertia, keeping it in orbit. Even if it suddenly loses some inertia, it falls to a lower orbit and won't fall into the sun, as its inertia increase again due to conservation of angular momentum. So, if a thing fall near a black hole, shouldn't it make...

Homework Statement 1. A diver jumps from a height of 10m leaving with a velocity of 8m/s find the time for which the diver is in the air and the speed at which the diver enters the water? 2. A ball is launched from point A on a horizontal plane with an angle of 55*. It passes two walls both 2m...

When stopped at a red light during a thunder storm, I notice this: - I hear the intensity of the rain hitting the roof of the car - there is a lightning flash - for a couple of seconds the rain intensity eases up noticeably, then resumes - then the thunder clap follows a little bit later It is...

Homework Statement Solve free fall from height h to the Earth´s surface in the place longitude φ. During solving, Consider gravitation acceleration as a constant for the whole trajectory, so g=constant. (consider a homogeneous gravity field) and variables which are including angular speed ω...

Hi, I would need some help with my homework. I am lost. Solve free fall from height h to the Earth´s surface in the place with geographical width φ. During solving, omit addiction gravitational acceleration to the distance. (consider a homogeneous gravity field) and variables which are...

Hi, I would need some help with my homework. I am lost. Solve free fall from height h to the Earth´s surface in the place with geographical width φ. During solving, omit addiction gravitational acceleration to the distance. (consider a homogeneous gravity field) and variables which are...

Homework Statement An object is thrown with speed 20 m/Sunder the angle pi/3 rad with the horisontal direction. In the highest point, the object is divised into two pieces with same weights. One of them, after the division has the speed 0. How far from the starting point do the pieces fall on...

I often see textbook recommendations here that about rigour and depth of coverage. Serious books for serious people! This question is different. I'm looking textbooks that inspire a love for mathematics. And I want to come at it from two different angles: (1) is there a textbook that was so...

How does this work exactly? I can understand depending on frame of reference but I read that Einstein stated there is a right way to think about that based on inertial and non-inertial frame of references.

Months ago I have seen walter lewins first lecture on dimensions, there he made a comment that scientist are trying to prove that time taken to reach ground when a object is dropped does depends on mass (in small amount) but it depends on mass, how they have thaught that it depends on mass ...

If I were to throw an object in the air from the ground and it would reach 50% of its maximum height in 2 seconds, how does one find the object's total maximum height and total travel time? This is the last question in my 1D kinematics chapter. I've been successful in resolving my other...

So I will be entering my big state U in two weeks as a freshman. I have down physics as my major because I have such a passion for the sciences and math however I am very torn if this is a right choice. I applied to my schools engineering school for the spring semester yet look through job...

I have a question. Does this schedule look heavy or easy to handle? Organic Chemistry 1 Tuesday and Thursday 11:00-12:15 Tuesday lab: 1:00-4:50 General Biology 1 ( not sure, because I won't take it unless it will be useful for General biochemistry) Monday and Wednesday 3:00- 4:15 and Monday...

Two girls are standing on a bridge over a river. One girl falls freely and the other ties a rope to her legs. Both jump at the same time from the bridge. The length of the rope is more than the vertical distance between the bridge and the river so that the rope never becomes taut till she...

I have found an article about an experiment that states that gravity on a small scale doesn't experience quantum effects. Of course the headline has been catchy, so I want to ask about the real importance or relevance of the experiment. Or for short: Do the results imply any consequences on...

Okay so first of all forgive me if I sound dumb, and forgive my english, is not my primary language. So I know two objects will fall at the same rate if air is excluded, so what I am asumming its that free fall formula is only correct if there's no air, right? So I am a programmer and I want to...

Why Is It That An Apple Will Fall On The Earth And Not That The Earth Will Live It Position And Move To Strike The Apple.is it just because that Earth has gravity. and Earth is a huge place very big material?

Do animals also fall in love? But first.. what is the difference between "in love" and "love?

Homework Statement I'm trying to write a program to calculate Newtons of impact force from a fall given the weight, general size, shape, and density of an object. I want to take air resistance into account. I also want to take the density of the thing the object falls on into account. I am...

Homework Statement Part C of problem Please see attachment : What is the minimum horizontal force needed to keep the book from slipping. Note that P=515N, and P=normal force, Fs=131.32N, Us=.255, M=9.85kg Homework Equations Fn=(m*g)/Us The Attempt at a Solution My answer is 378.549N, which...

Could someone tell me an application of the model of free fall to industry or more generally by using Newton's second law and the law of gravitation, construct a model similar to the free fall one, that has an application in industry

Homework Statement Two masses, M and m, are initially (at time t=0) at rest with respect to each other and separated by a distance d. They are affected only by their mutual gravitational attraction. Find the amount of time elapsed beginning at the instant the separation is equal to d/2 and...

Ok so what I want to create is a simulation of how the acceleration of a person falling would change according to the person's mass and height. This would then be explored in Matlab. Therefore, first, I am trying to find out the equations that would relate acceleration motion with mass and...

Homework Statement An object is in freefall on Earth. Which of the following statements is true? A) The object is gaining an equal amount of momentum for each second it is in free fall.B) The object is gaining an equal amount of momentum for each meter it falls.C) The object is gaining...

Hello - I have a question from a CSET practice exam that I'm having trouble understanding the provided answer. Q Two items are dropped simultaneously from a ten-story building. The items are shaped similarly and are relatively the same weight. Which of the following statements is correct...

Homework Statement A person of weight w is in an upward-moving elevator when the cable suddenly breaks. What is the person's apparent weight immediately after the elevator starts to fall?