Escape Definition and 374 Threads

Homework Statement The problem is attached Homework Equations L=mr^2(dr/dt) V_escape=(GM/R)^.5 E=L^2/(2mR^2)-(GMm)/R=0 The Attempt at a Solution after some work i got: dr/dtheta=((r^3/R)-r^2)^1/2 dont know what to do from here. Thanks.

So I looked at a neat derivation for what the minimun escape velocity is, and It was pretty clever. Because this is conserved: KE + PE = 1/2 *mv^2 + -GMm/r You can find what the velocity would have to be to get to infinity with zero velocity 1/2 *mvesc^2 + -GMm/r = 1/2 *m(0)^2 +...

can someone explain physically why escape velocity is independent of angle of projection.

Okay, in the Escape Velocity Equation, with the usual notations, v2=2gR2/r + (v02-2gR) a few articles like [PLAIN]"www.math.binghamton.edu/erik/teaching/02-separable.pdf"[/URL]give the following explanation: ... ... ...(implying that v0>=√2gR) That raises a few doubts in my mind...

: Derive a relation for the escape velocity of an object, launched from the center of a proto-star cloud. The cloud has uniform density with the mass of M and radius R... Ignore collisions between the particles of the cloud and the launched object. If the object were allowed to fall...

"Given a planet has mass M and radius R, find the speed it would have to be launched at. Compare this to the speed required to put the object in the circular orbit." I understand the first half where Ep=Ek i.e: GMm/r = 1/2 mv2 rearrange to find v how ever, I'm unsure of what exactly...

There is a jetstream of particles (mostly electrons and photons) coming out of the black hole. But nothing escapes from a black hole because its gravity is so strong. So how do these particles come flying out of a black hole?

Homework Statement A satellite is in orbit around a planet with orbital speed determined to be 7080 m/s. Find the escape velocity from the planet from this position of its orbit. Homework Equations EV=sqrt(2GM/r) The Attempt at a Solution With a problem like this, I would just...

Earth's Escape velocity is approximately 11.2 km/s, which is derived from the equation v = (2GM/R)^1/2. I know that this equation is derived from energy conservation, K + U = 1/2mv^2 + (-GMm/r). My question is regarding the addition of other masses to this equation based on location...

how can hawking radiation escape from a black hole? thanks

Is there a certain material that absorbs X-Rays so that the X-Rays don't escape. Or rather, is there a material that stops the X-Rays from continuing. If there is such a material, is there a way to change the X-Ray into an electrical current?

Greetings, The event horizon of a black hole is supposedly a point of no return. But can't the presence of another gravitational source decrease the event horizon? If you are between two sources of gravity isn't it easier to move away from either one? If immediately after a particle crosses...

Hello, I am aware that this question was the subject of a topic on this site, but it did not fully answer my question. My question is, why can't light escape from a black hole's gravitational pull, when, according to general relativity, the speed of gravity is equal to the speed of light? My...

maybe this will make it easy for you to understand. when in Earth at a radius of 9.27e4, you tell me what the escape velocity is? when in the moon at a radius of 2.14e4, you tell me what the escape velocity is? when in the sun at a radius of 6.43e6, you tell me what the escape velocity...

v=(gr2)^.5 i assume that g is directly related to r as g = Gm/r^2 in such I started to wonder when, if ever, will v = r as an INTEGER ONLY NOT DIMENSIONS? v = ( 2 * g * r )^.5 v = ( 2 * G * ( m / r^2 ) * r )^.5 v = ( 2 * G * m / r )^.5 v * r^.5 = ( 2 * G * m )^.5 REMEMBER! v=r at some point...

Hi guys! I want to ask something about escape velocity. I know the definition of EV "escape velocity is the speed at which the kinetic energy plus the gravitational potential energy of an object is zero"(wikipedia). Can we approach the problem by equalling the attractive force to the...

Homework Statement A spaceship is launched from the Earth's surface with a speed v. The radius of the Earth is R. What will its speed be when it is very far from the Earth? (Use any variable or symbol stated above along with the following as necessary: G for the gravitational constant, m for...

How to calculate the fraction of stimulated photons that escape from a laser cavity with alpha=0.1 cm^-1 length of cavity=1mm refractive index of laser cavity=3.2 the photons are assumed to be escaping into air so approx refractive index is 1. Im assuming that alpha is some sort of...

Homework Statement A 20000kg spacecraft carrying 17000kg of fuel starts at the surface pf the earth, (Mass=6*1024kg, radius of 6.3*10^6 m). The liquid oxygen and kerosene rocket provides an exhaust velocity of 3500m/s. a.) How much high can the rocket go above the Earth's surface? b.)Once...

Homework Statement A scientist wants to put an 100kg experimental package in orbit around the Earth. The cost of deployment depends on the amount of extra energy it takes to get it into the required position i.e. how much more energy is used than just sending the rocket up there. a)...

Homework Statement A spherical asteroid has a density of 2600 kg/m^3. I throw a ball at the speed on 20 m/s. If the ball is to travel in a circular orbit, what is the largest radius of the asteroid possible to accomplish this? Homework Equations these are the equations I used.. escape...

Homework Statement An Object is fired vertically upward from the surface of the Earth ( of radius RE ) with an initial speed vi that is comparable to but less than the escape speed vesc Show that the object attains a maximum height h given by h=\stackrel{R_{E}v^{2}_{i}}{v^{2}_{esc}-v^{2}_{i}}...

A 75 kg petty third wants to escape from a third story jail window. Unfortunately, a makeshift rope of sheets tied together can support a mass of only 50 kg. What is the minimal acceleration with which the thief must lower himself so he may use the "rope" without breaking it? the variables i...

Ok, this might seem like a silly question, but I just want to get it straight. Just tell me if anything I am saying is wrong, and answer the best you can. Ok, the moon has no air, because it has no atmosphere correct? And the reason for no atmosphere is because the moon is biologically...

Homework Statement estimate the radius of the largest asteroid from which you could escape simply by jumping off. Homework Equations R^2= 3gh/4piGp The Attempt at a Solution Would I use this formula to solve it? Found it online but dose not seem right. this is a 2 part problem...

I am trying to understand the existence of orbits apart from the elliptical one. I have used the following line of thought. Consider an object moving from infinity towards a planet. The object has kinetic energy alone at infinity. But it develops a potential energy as it comes closer to the...

I have a problem where it ask to find the period/time(using Kepler's 3rd law) of an unpowered spacecraft to move from Earth's orbit to Mars orbit using the transfer orbit approach. I found P/T using kepler's 3rd law but the second part ask to find how fast the spacecraft need to be moving at...

Homework Statement [PLAIN]http://img443.imageshack.us/img443/3598/physicsproblem.png Homework Equations Ok so I am first of I don't know when they said layer if they meant the number of people or the thickness? of the people I don't understand the question The Attempt at a Solution what I...

I tried finding the equation for terminal velocity in a broader attempt to understand planetary orbits better. According to wikipedia's two derivations (one of which i don't understand very well) I'm off by a factor of \sqrt 2 . I would greatly appreciate help in finding my thinking/math...

http://img682.imageshack.us/i/77482562.jpg/" I don't really understand these questions... Is there anyone who could tell me HOW to solve them? I don't ask about ONLY answers, I just want to understand how to solve these types of exercises. The things I know: 1. the centrifugal force =...

I have been told that there is no interaction between the gravitational fields of the sun and any planet, but the issue continues to stimulate my curiosity. If the Earth orbits the sun at 30km/s, how could anything achieve an orbital speed around Earth at greater than 30km/s without...

Homework Statement Three wires are made of same materials. Which wire will have the greatest elongation? wire1: length: 50cm, diameter: 0.5mm wire2: length: 100cm, diameter: 1mm wire3: length: 300cm, diameter: 3mm Homework Equations The Attempt at a Solution I know, the wire having greatest...

electricffiled..calcuate escape speed! urgent please help Homework Statement Homework Equations ke=1/2mv^2 Ue=Eqs E=kq/r^2 The Attempt at a Solution Uf+kf=Ki+Ui Uf=0 and Kf=0 so -Ui=Ki Eqs=1/2(mv^2) v=(sEqs/m)^1/2 after this no clue i got lost help please

I was trying to understand the similarities and differences between electrostatics and standard Newtonian mechanics, in particular gravitational formulas. One thing I was curious about is escape velocity. For gravity I've learned that it's sqrt(2GM/R). But for electrostatics, suppose I was...

Homework Statement A certain spherical planet which is not rotating has a radius of 6.36 x 105 m and a mass of 1.89 x 1021 kg. At what minimum speed would a vehicle traveling along its surface just begin to leave the ground? Homework Equations FC = mv2/r FG = GMm/d The Attempt at a...

Sagitarius A or SgrA is a star rotating near the center of our Milky Way Galaxy. Located at Ecliptic Longitude of 27sgr00 right now. The velocity of SgrA must be tremendous. What is the prognosis that it will collide with the black hole? This supermassive Black Hole will soon engulf...

Homework Statement I'm having a hard time relating the escape velocity equations, sqrt(2GM/r) to sqrt(2gr) The Attempt at a Solution I know that both equations mean the same thing, but I can't figure out how to get from the first equation to the second

If light can't escape a black , Then can a magnetic field escape a black hole , If the B field has an energy density , and if it has energy associated with it then it should be affected by gravity .

Homework Statement A projectile is shot directly away from Earth's surface. Neglect the rotation of the Earth. What multiple of Earth's radius RE gives the radial distance (from the Earth's center) the projectile reaches if (a) its initial speed is 0.225 of the escape speed from Earth and (b)...

Homework Statement What multiple of the energy needed to escape from Earth gives the energy needed to escape from (a) the Moon and (b) Jupiter? Use the Table (link below) if necessary http://edugen.wiley.com/edugen/courses/crs1650/art/qb/qu/c13/fig13-19.gif Homework Equations...

Hello guys, This is simple question but I have gone completely blank. Ok let's say there was a balloon outside that was inflated. This means that it has expandes so it's pressure is equivalent to atmpospheric pressure right? So when I pinch it why does air escape, how does balloon suddenly...

Homework Statement A satellite with a mass of 5.00x10^2 kg is in a circular orbit, whose radius is 2re, around Earth. Then it is moved to a circular orbit with a radius of 3re. e) Calculate the escape velocity for the satellite if it is on Earths surface. Homework Equations Vesc =...

Homework Statement A projectile is fired from the Earth in the direction of the earth’s motion around the sun. what minimum speed must the projectile have relative to the Earth to escape the SOLAR SYSTEM? Ignore the earth’s rotation. Homework Equations escape velocity = sqt[(2G x...

\sqrt{}Homework Statement What is the escape speed (in m/s) of an electron launched from the surface of a 7.42 cm diameter glass sphere that has been charged to 7.04 nC? Homework Equations u=kqq/r KE=1/2MV^2 UO=KE The Attempt at a Solution here is what i did kqq/r = 1/2mv^2...

Consider a spoked wheel of radius r. The instantaneous tangential velocity of a point on the rim is v. A test particle in the form of a small bead that can freely slide along a spoke when released, is placed as close to the axis as possible so that for the sake of argument its radial...

A certain planet with a radius of 8.30×107 m has an escape velocity of 3.60×104 m/s. What is the mass of this planet? How do i solve this?

I've heard that the moon is very slowly moving away from Earth. Will it eventually escape Earth's orbit?

Okay this equation is giving me some trouble, I just have a question vescape = √(2GM)/R Say I wanted to find the escape velocity of myself 3 meters away So I would use vescape = √(2)(6.674*10^-11)((145*4.44)/9.8)/(3) = 5.419003598 *10^-5 So does this mean something that moves that slow cannot...

Okay, I just found this new equation (new to me) for the escape velocity of a body. escape velocity = √(2GM)/R So say for instance I plug this into the escape velocity of the earth I am going to say the radius is 4001 miles so I it would take a mile above the Earth to escape (4001 * 1600) =...

http://curious.astro.cornell.edu/question.php?number=760 Yep, it's an exception to the rule that "nothing can escape a black hole".