Free fall Definition and 479 Threads

In Classical GR the metric tensor ##g_{\mu\nu}## determines the length of rods and ticking of clocks while the connection ##\Gamma^{\alpha}_{\mu\nu}## determine the equation of geodesic (the free fall motion of particle). Furthermore, in GR the Levi-Civita connection is uniquely determined by...

I was doing some conceptual problems quickly before moving on to the numerical stuff when I glanced at this answer given in the solutions manual, and it surprised me: Which object has greater speed at the bottom of its fall, object A of mass m dropped freely from height h or object B of mass m...

Hello, Let us imagine a solid in a free fall on planet Earth and let us neglect the effect of air resistance on the motion of the solid. According to Newton's Second Law of Motion, since the only force being applied on the solid is its Weight, then its acceleration must be its Weight divided by...

Homework Statement which one would be faster when reached the ground? Homework EquationsThe Attempt at a Solution conservation of energy Pe=Ke mgh=1/2mV^2 for 2-)m*g*cosa*(h/cosa)=1/2*m*V^2 -- V= sqrt(2*g*h) for 1-) V=sqrt(2*g*h) so V1=V2

For many, many years (don't ask), I've been running into the classic example of the local reference frame: the man in the box who can't tell if he's floating free in space, or falling into a gravity well. It occurs to me that if one is in a falling box, a mass released at the top of the box...

Homework Statement We release m_o = 1 kg object from h=1m height. How much does the Earth move (x)? I just need the comfirmation if I did correctly? Homework Equations Conservation of momentum: m_o v_o + m_E v_E = 0 The Attempt at a Solution I wrote the energy conservation law as (beginning...

Homework Statement The reason why the heavy stone and light stone fall equally because of the ration of force to mass is same. can you explain it please what is ratio of force to mass is same?. Homework Equations F=ma and F=Gm1m2/r² The Attempt at a Solution As their acceleration is same...

Homework Statement A body is falling from a height of 720m. Divide this distance into three parts so that the body would overcome all parts in the same time. P.S (This is translated from a different language) Homework Equations x(t)= x0+V0+at2/2 v(t)=V0+atThe Attempt at a Solution I made an...

<Moderator's note: Moved from a technical forum and thus no template.> An object with mass 96 kg is given an initial downward velocity −3m/s in a medium that exerts a resistive force with magnitude proportional to the square of the speed. The resistance is 60 N when the velocity is −2m/s. Use...

The equations of a falling object dropped from a 1000 foot tall building are simple: eq 1 ##s=1/2( at^2)## eq 2 ##v(final)=(2as)^.5## eq 3 ##v(final)=at## where a is the acceleration due to gravity at the surface of the earth s is the height of the building, t is the time it...

Homework Statement A boy release ball A from height 5m from ground at the same time other boy throw ball B vertically upward to exactly strike ball A. When ball B released it was 1m from ground find minimum initial velocity of ball b. Given g=10m/s^2 a) 2m/s b) 3m/s c) 4m/s d) 5m/s Homework...

Hello, so i know in a free fall the acceleration is constant (9.8 m/s2) therefore speed/velocity is increasing.. But I am wondering why we can't use Speed=D/T

This is something I haven't been able to wrap my head around yet. In physics, I've always been told that gravity is a force that ALWAYS works between "objects" with mass. Now, it seems clear to me that if a feather and a hammer were to be dropped at the same time on Earth (without air...

If an object with 1kg mass falls free (no air drag), from 100 meters high, and the gravitational acceleration is 9.81, then the mechanical energy will be: 1*9.81*100 = 981 joules. The work the gravitational force does on the object will be: 9.81N*100m = 981 joules. Another object with same...

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?

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...

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...

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...

If two people are free falling from the sky at the same (high) speed, at the same altitude, but about 20 meters away from each other, and one of them has a gun and tries to shot the other, do they aim directly at the other person so they get a hit (because the bullet would also be falling), or...

If there is a ball falling from a height due to gravity, and you keep your hand still and let the ball fall onto it, it stops suddenly and makes a loud noise. However, if you lower your hand as you catch the ball, like when a cricketer catches a fast moving ball, the catch is almost silent. I...

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...

Hi all, Background: I'm working on a project where I am dropping an arduino with an accelerometer from ~100 ft in the air to measure it's acceleration during free fall and at impact. I need to compare my collected data with predicted models. I have the model for free fall (just 9.8m/s^2)...

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'...

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...

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...

Homework Statement sportsman jumps at 5m/s velocity from 5m cliff to water. at what speed does he reach water? so given answer is 11.1m/s though in this book there are some wrong answers (I did try other equations and I got right answer but I want to know why I can't get it using this one)...

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...

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.

Homework Statement I work as a supplemental instructor for an intro physics class. As I was preparing my worksheet for this week I came across this problem. A basketball player can jump to a height of 55cm. How far above the floor can he jump in an elevator that is descending at a constant...

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 ...

Hi I'm trying to solve a problem but I'm a bit confused about this part: Suppose you are walking at a speed of 2 m/s when you drop the ball that you were holding in your hands. Is the initial velocity 0 m/s? In the textbook it says that initial velocity for dropped objects is 0 m/s but that...

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...

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...

Homework Statement Bindi pops the cork off a bottle of champagne. The cork travels vertically into the air. She notices that the cork takes 4s to return to starting position. a) how long does cork take to reach maximum height? Homework Equations I know that a= -9.81m/s/s, and the final...

why spacecraft launches are usually terminated at either perigee or apogee?

Could someone explain under which principle does Skinner's machine operate? Is it just a free falling mass that's taken back to it initial position by very little input energy, thus generating a constant gradient or potential difference, and generating energy, or is it just storing kinetic energy?

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 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...

Hello I have a projectile project. we throw an object with variable speed but about 80 mps and about 90 degrees from Earth level. our goal is to find maximum height that is usually between 250 to 350 meters by means of 3 axis accelerometer and 3axis gyro ( MEMS technology ). In fact we use...

Centrifugal force due to rotation of the Earth has among its effects the deviation towards the equator of a ball falling from height ##h## vertically on Earth. I do not understand what is the inertial explanation of this phenomenon. Once the ball is released there is no centripetal force that...

Homework Statement A balloon is ascending at an speed of 13 m/s. At 300 m from the ground a ballast is drop from the balloon. Find the maximum height the ballast reach. My doubt is: When the ballast is drop ¿it starts falling inmediately?. The solution of the problem implies that the ballast...