Gravitational potential energy Definition and 291 Threads

Gravitational Potential Energy (U) = -(GMm)/R Also, U = mgy. I need help making a connection between these two equations. For U = -(GMm)/R, it is saying that because R = radius of the Earth, an object on the surface of the Earth has a gravitational potential energy, correct? U = mgy seems to...

Homework Statement Estimate the gravitational potential energy released in the collapse of a 1.2 solar-mass core from an initial density of 10^9 g/cm^3 to a final 10^15 g/cm^3. Homework Equations The Attempt at a Solution The book doesn't provide much guidance on this. I was thinking of...

Hello, I'm currently studying Gravitation and circular motion. I have a question on the reference point for gravitational potential energy: In previous units, gravitational potential energy was usually measured from the surface of the Earth (the ground in most cases). Why when an object is...

Hi, I've been thinking on this for a while, any help would be great :) I have a box placed over a table. There's a pen kept over the box. What I do here is move the pen slowly, without changing its velocity and bring it down on the table. Assuming the table and box are at a height h1...

Homework Statement A high jumper of mass 60.0 kg consumes a meal of 3.00 x 10^3 kcal prior to a jump. If 3.3% of the energy from the food could be converted to gravitational potential energy in a single jump, how high could the athlete jump? Homework Equations Ug = mgh gravity =...

I have two physics books that state that U(r) = -GMm/r What I don't understand,is how can potential energy be negative? I've done the integral of GMm/r^2 from infinity to r, but I don't quite get the concept of negative potential energy. I don't understand why using r=infinity as...

Homework Statement [PLAIN]https://dl.dropbox.com/u/9215647/webassign%20s.JPG Rank the slopes (greatest first) according to the work done on the skater by the gravitational force during the descent on each slope, Homework Equations work=change in potential energy, ie. delta U =...

Homework Statement Hi everybody, this is a conceptual question about gravitational potential energy that my textbook and high school teacher seem to give incomplete answers. The problem involves two masses m_{1} and m_{2}, where m_{2} > m_{1}, which are both at a radius R from the Earth's...

Homework Statement Here is the problem: http://i51.tinypic.com/6r7jts.jpg Homework Equations PE= mgh KE= 1/2mv^2 I'm not sure how to go about this problem =[

1. A system consists of three particles, each of mass 1.90 g, located at the corners of an equilateral triangle with sides of 31.0 cm. Calculate the potential energy of the system. 2. Homework Equations : U= -(Gm1m2)/r G = 6.67x10^-11 Nm^2/kg^2 3. My attempt: I would think each particle...

1. Is it possible to caculate the electric potential energy and the gravitational potential energy between two nucleon of deuterium (1 proton, 1 neutron), if we know the binding energy of deuterium is 2.23 (MeV), and the distance between them is 1 (fm)? Please help me! I'm really confused about...

Homework Statement What is the change in gravitational potential energy of a 6200 kg satellite that lifts off from Earth's surface into a circular orbit of altitude 2500 km? What percent error is introduced by assuming a constant value of g and calculating the change in gravitational potential...

Homework Statement An ATV(all terrain Vehicle) of 2000kg mass moves up a 15 degree slope at constant speed os 6m/s. What is the rate of change of gravitational potential energy with time. note power= change of U/change t a 5.25 kw b 24.8 kw c 30.4kw d 118 kw Homework Equations...

I'm really stuck with this last question...im not quite sure where to start...any help would be greatly appreciated! for a) I am not sure what to use for the mass of the star and the radius..do i have to subtract the two radii? When a massive star is at the end of its life, the inner core...

Homework Statement An all-terrain vehicle with a 2,000 kg mass moves up a 15o slope at a constant velocity of 6 m/s. What is the rate of change of gravitational potential energy with time? Homework Equations W=\DeltaE/\Deltat W=FXd Ki+Ui=Ki+Ui (I think that's what it is) Pe=mgh...

Help! gravitational potential energy? i have one more chance someone please help me!

Homework Statement A 0.720 kg snowball is fired from a cliff 8.10 m high. The snowball's initial velocity is 14.2 m/s, directed 30.0° above the horizontal. (a) How much work is done on the snowball by the gravitational force during its flight to the flat ground below the cliff? (b) What is the...

Homework Statement A satellite of the mass 500kg is boosted from an orbit of altitude 10,000 km to one of altitude 20,000km. Given that the diameter of the Earth is 12,756km, its mass as 5.97x1024. calculate the change of GPE of the satellite Homework Equations Ep=-Gm1m2/r + altitude...

In deriving the gravitational potential energy term I have a question. W \ = \ \int_{r_1}^{r_2} \overline{F}( \overline{r}) \cdot \,d \overline{r} \ = \ \int_{y_1}^{y_2}mg \,dy W \ = \ \int_{y_1}^{y_2}mg\,dy W \ = \ mgy_2 \ - \ mgy_1...

Homework Statement You see an optical illusion of an ever-upward spiral staircase. The climber trudges up and up and never gets anywhere, going in circles instead. Suppose the staircase is provided with a narrow ramp, allowing the tired stair-climber to push a wheelbarrow up the stairs. The...

Homework Statement Seiche in a lake. The simplest motion of water in a lake can be approximated as simply the water surface tilting but remaining flat. Imagine a lake of rectangular cross section of length L and with depth h where (h<<L). The problem resembles that of the simple pendulum, the...

Homework Statement Derive the gravitational potential energy from Newton's law. Homework Equations \mathbf{F} = -G \frac{m_1m_2}{\left|\mathbf{r}\right|^3} \mathbf{r} W = \int_A^B \mathbf{F} \cdot{} d\mathbf{r} \Delta{}U = W The Attempt at a Solution I can use the scalar version of...

Hi I'm just going over some revision questions and there's this one question where I'm not sure if my working is correct (we don't get given the answers). Homework Statement A bobsled is moving at 3m/s as it passes a timing location. It then descends through a height of 3m before passing...

I'll first derive here the gravitational pot. energy by my method, and then I'll give the method that has been formally used in books. My answer differs from the actual one by a minus sign. My derivation: Let mass M be at the origin O. Let another mass m be at an arbitrary position r from...

I was doing some reading on X-ray binaries and got to reading the wikipedia article on it: http://en.wikipedia.org/wiki/X-ray_binary When I read this line: "The infalling matter releases gravitational potential energy, up to several tenths of its rest mass, as X-rays. (Hydrogen fusion...

So, I've heard that if you lift a boulder into the air, it's mass increases slightly as per e=mc^2. Well, my question is, does gravity act on this new mass? If so then shouldn't it have slightly more gravitational potential energy, and thus slightly more mass etc. ad nauseum? Would the...

Homework Statement Consider a large uniform ring having a mass of 2.36x1020kg and a radius 1.00x108m. An object with a mass of 1000kg is placed at a point 2.00x108m from the center of the ring. When the object is released, the attraction of the ring makes the object move along a straight...

Homework Statement a 5.00 x 10^2 kg satelilite is in circular orbit 2.00 x 10^2 km above Earth's surface. calculate a) gravitaional potential energy which i got, which is -3.13 x 10^10 J b) kinetic energy of the satellite c) binding energy of satellite d) the percentage increase in...

Exactly what the title says. I wonder if gravitational potential energy close to the Earth is something intrinsic in the object that can be measured or is it completely dependent upon where we consider our 0 level to be. For example if we lifted an object a distance h above the ground and set it...

Here is a summary, written by me, of an experiment I carried out: Is the method correct (if you recognise the experiment)? Are the results and conclusion correct (do any of the figures/calculations seem significantly wrong)? Is there anything more I could say for the conclusion? Any ideas...

HEre is the page! http://img190.imageshack.us/i/backofgravitationalpote.jpg/ Homework Statement http://img190.imageshack.us/i/backofgravitationalpote.jpg/ Qeustions at that pg 1.Examine teh graph 2.Calculate the change in potential of a 25 kg mass which is placed into orbit 520 km...

Im not talking about eg=mgh.. I am talking about deltaEg=(GMm/r1)-(GMm/r2) My question is how is it possible to say that in General , Eg=(-GMm/r) and why does Eg not equal 0 when r -> infinity Thanks please reply quickly :)

An interstellar gas cloud can be roughly described as spherical with a uniform density. Its radius is R and its total mass M. By considering the gravitational potential energy of a thin spherical shell, show that the total potential energy of the cloud is given by...

Homework Statement A satellite in a circular orbit around the Earth with a radius 1.019 times the mean radius of the Earth is hit by an incoming meteorite. A large 73-kg fragment is ejected in the backwards direction so that it is stationary with respect to the Earth and falls directly to the...

Homework Statement A satellite with a mass of 5.00 x 10^2 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. a) Determine the satellite's gravitational potential energy in each orbit. Homework Equations Ep= -GMm/r...

I'm still on special relativity, and haven't yet reached general relativity, but had a question in mind... does the Newtonian description of Gravitational Potential Energy U= -G \frac{M m}{R} fail for very strong gravitational fields? or it only fails where curvature of space becomes...

Homework Statement A rocket is accelerated to speed v=2√gR (where R is the radius of Earth 6370 km) near Earth's surface surface and it then coasts upward. a) show that it wil escape from Earth. b) Show that very far from Earth its speed will be v=2√gR. Homework Equations Gravitational...

http://session.masteringphysics.com/problemAsset/1125570/2/Walker4e.ch12.Pr042.jpg use this image for help a. Consider the four masses shown in the figure . Find the total gravitational potential energy of this system. b. How does your answer to part A change if all the masses in the...

Homework Statement How high above the surface of the Earth must a mass be located so its gravitational potential energy is only 17.00% of its value on the surface? Homework Equations PEg=(-GMm)/r, PElocal= mgy where y is height the object can fall The Attempt at a Solution...

Homework Statement Assume no friction. A 58-kg teenager at a water park slides down a long, winding waterslide of varying slope. The slide has a net height difference of 30. m from start to finish, and the teenager starts from rest. Throughout the problem, let y=0 and Ugrav = 0 at the end...

Hello, I have been trying to get my head around the concepts of energy, work and momentum. I am trying to build some testing equipment to measure the "transfer of energy" of a moving object striking a pendulum type mass, but am unsure if my physics is correct. The image attached is my idea...

Homework Statement The magnitude of the attractive force of gravity between two massive bodies is F=GMm/r^2, where G is a constant, M and m are the masses, and r is the distance between the centers of the two bodies. The radius of the Earth is 6.38×10^6 m and its mass is 5.97×10^24 kg. A...

Homework Statement a 18.5 kg box is slid up a 5.6 m long ramp that makes an angle of 33 degrees with the floor. What is the gravitational potential energy of the box relative to the floor? m = 18.5 kg d = 5.6 m http://musr.physics.ubc.ca/~jess/symbols/Theta.gif = 33° PEg = ?Homework Equations...

Homework Statement A person weighing 6.0 × 102 Newtons rides an elevator upward at an average speed of 3.0 meters per second for 5.0 seconds. How much does this person’s gravitational potential energy increase as a result of this ride? (1) 3.6 × 102 J (3) 3.0 × 103 J (2) 1.8 × 103 J...

Hi there, As we know gravitational potential energy is U = -GMm/R right? Here is what i obsessed, in case for the each particle can we say half of this energy belongs to one particle? I hope my question is clear enough:) Thanks in advance.

Hey guys, Do any of you happen to know how to derive the formula for General gravitational potential energy (not the mgh one) without using calculus? Thanks. Just in case you guys want to know, I'm trying to derive the equation for this: http://xkcd.com/681_large/. I've got most of it, but I...

hi, i don't really understand the meaning to GPE. if we define a point at infinity to have 0 GPE, then any point before infinity would have -ve GPE. so let's say an asteroid crashing to Earth at the surface of the Earth has initial kinetic energy of 1/2mv^2 and GPE of -GMM/r so E(total)...

1. An acrobat on skis starts from rest 50.0 m above the ground on a frictionless track and flies off the track at a 45.0 degree angle above the horizontal and at a height of 10.0m. disregard air resistance. what is the skier's speed when leaving the track? 2. K=.5M*V^2 and U=M*g*h...

Homework Statement (a) Determine the energy, in kW·h, necessary to place a 1.0-kg object in low-Earth orbit. In low-Earth orbit, the height of the object above the surface of Earth is much smaller than Earth's radius. Take the orbital height to be 300 km. G = 6.67*10^-11 Me = 5.97*10^24 Re =...

[SOLVED] Elastic and gravitational potential energy First off, long time lurker here on his first post. Your forum seems absolutely brilliant, so I hope you can help me :) Homework Statement A box on an elastic string is dropped down an incline and proceeds to slide the distance L before...