Potential energy Definition and 1000 Threads

Homework Statement A small metal sphere, carrying a net charge of q1 = -2.90 μC , is held in a stationary position by insulating supports. A second small metal sphere, with a net charge of q2 = -7.20 μC and mass 1.70g , is projected toward q1. When the two spheres are 0.800 m apart, q2 is...

Hello, Firstly i am new here ( not offering an excuse) and an on and off lurker to this awesome forum. I am trying my best to fit into the established rules ,sorry if i broke any inadvertently. If kinetic and potential energy represent the same things why are there entities representing the...

Homework Statement Now , I Will Begin by stating the calculation and i will post the query at the end. so here we begin, we know that If W is the work done by a conservative force, potential energy change is given by: ΔW= - ΔU ...(1) ie when work done by conservative force is positive...

Where does the potential energy go?? hello.. One of my friend asked me this question, and i had no answer to it. moreover the professors response to it seemed unsatisfactory. The question is: Suppose we have a dipole in a uniform External Electric field, which causes it to rotate (or...

First of all, my question isn't completely unrelated to a homework question. I know how to answer that question using definitions in the book and mechanically get to the end. But I wanted to start from basic principles and arrive at the same answer. This lead to a contradiction which sent me on...

Homework Statement Write the cartesian equations of the movement of a material point of mass m that is in a forces field in which the potential energy is V(x,y,z)=-αy^2 , and you know that at time t=0 the point is in the position which has coordinates (0,0,Z0) with velocity v=V0*j P.S...

Homework Statement "Two parallel plates having charges of equal magnitude but opposite sign are separated by 12cm. Each plate has a charge superficial density of 36nC/m2. A proton is launched from the negative plate to the positive plate. What is the minimum speed the proton should be...

Hello everybody. Imagine a box in which two spheres are separated by some distance. nothing is moving inside. Einsteins E=m*c^2 must be always valid. Since nothing moves the energy of box is E=m°*c^2 where m° is rest mass. Since the spheres exert gravitational force on each other they will be...

I was wondering if dark energy might actually be gravitational potential energy. If one assumes that space is flat and that the Universe is approximately a sphere with mass M and the Hubble radius R then we find that we have the approximate relation: \frac{G M }{R} = c^2 A mass m...

is it possible to construct a system with only finite number of point charges of arbitrary magnitude at finite distance from each other such that the total potential energy is zero everywhere? i doubt earnshaw's theorem would prohibit this construction, hence is it possible? thanks

Homework Statement A 10.0 kg block is released from point A in Figure P8.57. The track is frictionless except for the portion BC, with a length of 6.00 m. The block travels down the track, hits a spring of force constant k = 2250 N/m, and compresses it 0.300 m from its equilibrium position...

object is the shape of a ball 300 feet in diameter. (~100m) object weighs 100,000 lbs (~50,000 kg) object is at a depth of 1000 feet (~300m) I just need a rough estimate - you can use meters or feet or whatever, i don't care. salt or fresh water is fine but if there is a choice salt...

Homework Statement The mean diameters of Mars and Earth are 6.9 10^3 km and 1.3 10^4 km, respectively.? The mass of Mars is 0.11 times Earth's mass. (a) What is the ratio of the mean density of Mars to that of Earth? (b) What is the value of the gravitational acceleration on Mars...

Can anyone help me understand this equation: Work = ΔK + ΔU + ΔE (no heat). Where K is kinetic energy, U is potential energy, and E is internal energy. This is for nonconservative forces only right? I'm just confused about what if some potential energy is converted into kinetic energy...

datum 1 --------- E1=K1+G1+S1 =0+8(9.81)(-3)(sin37)+0 =-141.69 datum 2 --------- E2=K2+G2+S2 =1/2(8)(v^2)+0+0 = 4v^2 Frictional Force: 0.15x9.81.8 = 11.772Newtons U1-2= -11.722x2 = -23.544J E1+U1-2=E2 -144.69-23.544=4v^2 -42.0585=v^2 Can't square root...

Is there Gravitational Potential Energy on a horizontal surface? Example from Position 1 - 2

Hello Forum, potential energy is a form of energy that something has in virtue of occupying a certain position in space (gravitational potential energy, electric potential energy, etc...) What is, in the case of fluids, pressure potential energy? A fluid is said to have a certain...

Is what I am currently reading about. The book I am reading presents it by giving an example; it proposes lifting a mass without any acceleration through a height, h, with an upward force equal and opposite to its weight. Does that mean the net work done on this mass is zero? My hand still does...

Because I'm a bit confused... I know mechanical energy is potential energy and kinetic energy but I'm not sure of the exact definition of potential energy. Is potential energy (the subset of mechanical energy) the following? Gravitational potential energy Elastic potential energy Chemical...

Potential energy has always bothered me. Is it just an accounting trick to describe that energy is always conserved ( E = K + U)? Because if so, there are probably other ways we can describe this.

I have attached a discussion by R.Feynman where he derives the formula for gravitational potential energy using pure reasoning. I don't quite follow the reasoning and I have read the discussion many times yet can't get a grasp of things he says. With the discussion I have my doubts in red...

Is body at higher altitude having more potential energy than a body on Earth real.? Does this mean a person at 400th floor has more capacity to do work than a person on ground floor(concerning precisely) Or is concept of potential energy just introduced to satisfy law of conservation of...

Hey guys, I'm currently trying to get my head around the concept of gravitational potential energy; U_{r} = -\frac{Gm_{1}m_{2}}{r} My question concerns whether this relates to both bodies in the system individually, or together. That is, if I have two masses separated by a distance...

Homework Statement You have 3 charges, all +2.5 μC arranged on a field at positions (-3.0 cm, 0), (3.0 cm, 0), and (0, 3.0 cm). I have already calculated the stored electric potential energy to be 3.85 J. The question is: If the third charge (0, 3.0 cm) is released from rest, what is its change...

If you have a coil with its magnetic dipole moment perpendicular to a uniform magnetic field, μ × B says that there will be maximum torque since sin90 is 1. But at the same time, -μ dot B gives the potential energy and cos90 is 0. What I don't understand is how you can have torque at this angle...

Hey all. I have a question regarding potential vs. potential energy. Basically, from what I can tell, the potential energy is a property of the system as a whole (it has a single value in any given situation) while the potential is a property of each specific point in space. Would this...

Homework Statement A spacecraft is in circular orbit around the earth. with respect to a point below it on earth, it is traveling towards the east with speed v. Specify the reference state for potential energy. Homework Equations The Attempt at a Solution the total...

Homework Statement What is the gravitational potential energy of a car with centre of mass at a height h above the ground? On a level road the centre of mass is at a height of 0.1m above the ground. Homework Equations gravitational potential energy=mgh The Attempt at a Solution I would use...

Homework Statement A horizontal spring with spring constant 97.9 N/m is compressed 18.2 cm and used to launch a 2.96 kg box across a frictionless, horizontal surface. After the box travels some distance, the surface becomes rough. The coefficient of kinetic friction of the box on the surface...

Homework Statement A rectangular sheet of thin material is rolled into a portion of a circular cylindrical surface of radius r. It rests under the action of gravity on a fixed cylindrical surface of radius R, symmetrical about the vertical centre line as shown below. If rolled slightly to...

Homework Statement I have a physics lad research that's due tomorrow, the overall process is to work out how much potential energy will be stored in a bow, and the efficiency of the bow. First of all, I have a graph, with the plots Force Vs. Displacement (of a weight 'm' on a string). We...

So I was looking at the equation for Gravitation potential energy U = - Gm1m2/r This implies the energy is 0 as r→∞ However, if I lift a book above my head, wouldn't it have more potential energy than if it was lying on the ground, meaning as r (h) increases, potential energy increases? Where...

how does this change with introduction of another charge in its vicinity suddenly..and how does this vary as both charges repel each other after introduction of like charge.. btw I even wonder whether a electron which is outside a atom is in form of wave or particle..hope my questions are...

earth? Homework Statement Mass of moon - 7.3 x 10^22 kg Mass of Earth - 6.0 x 10^24 distance between moon and Earth - 356400 km change in distance 4 cm Homework Equations The Attempt at a Solution I just need to check if my answer is correct, I get some thing to the power...

Homework Statement This isn't a real HW problem for me but just a question I asked myself and I am slightly confused by the solution I get. Here is the situation. You have an infinite line charge and a point charge q. Find the potential energy given to the point charge from the infinite line...

If you are holding an object off the ground and let it go, we say that it's potential energy is transformed into kinetic energy as it falls, but the total amount of energy stays the same. However, the gravitational force is doing work on the object, which seems like it would increase the amount...

Hello all, I'm new to the forum here and desperately need some help in some basic physics concepts that I need to have a firm grasp on for the MCAT. My question is about PE on an inclined plane. For example, there are 3 possible scenarios (the height and mass remains the same for each...

I've Had this doubt from a long time back : Being in high school my physics teach simply stated that No explanations given. To quench my thirst I went through books and things . I found one difinitive result : a: In this Video http://bit.ly/wl8-0204 Prof.Walter Lewin Says...

Ok so a friend and I were talking and a question came up about where is the kinetic energy of an object stored? You see the whole idea is around the fact that kinetic energy is information right? So we thought of a thought experiment for this, lol. Let's say you are in a ship in space, there...

*URGENT* Elastic potential energy with box going up an incline. Homework Statement A spring having a force constant of 240 \frac{N}{m} is placed on a plane inclined at 67° to the horizontal. The spring is compressed 0.40 m and a 2.0 kg mass is placed on it. The coefficient of kinetic friction...

The text on wikipedia says that due to compton scattering, the electron is ejected from the atom, but if so, the difference in energies of the two photons will not appear entirely as its kinetic energy, some of it must be used to overcome its potential energy, i.e. binding energy must be...

Homework Statement Show that the potential energy of a system which consists of four equal particles, each with mass M, that are placed in different corners of a square with sides of length d, is given by ep = - \frac{G M^2}{d}*(4 + √(2)) Homework Equations The gravitational force F(r)...

Just a little confused, when work is done on an object it's energy increases right? (i.e. Work done on object = Change P.E + Change K.E + Work done by object) So how come when gravitational force does work on an object(i.e. it falls) the potential energy decreases instead. So its like Work...

Homework Statement The spring in the figure below is initially compressed by 0.4 m in the position shown. If released from this position, block A travels 0.9 m before coming to a stop. The kinetic coefficient of friction is 0.8. What is the spring constant? (The spring is not fastened to...

I'm missing something here... Using the equation for calculating GPE, I'm getting an odd result in an example involving a roller coaster. Assuming at the top of the hill we have 100% PE and 0% KE and the reverse to be true at the bottom, we should have 0 joules of gravitational potential...

Homework Statement The nucleus of a helium atom contains two protons. In a simple model of this nucleus, the protons are viewed as point particles separated by a distance of 1.0 fm (1.0 x 10^-15 m). What is the electric potential energy of the two protons? please do step by step.

Homework Statement Consider the force F=(y2z3 − 6xz2)i + 2xyz3j + (3xy2z2 − 6x2z)k. I've solved the first part of the problem that asked if the force was conservative (it was) and what was the potential energy of the force(U) U=-y2z3+3x2z2+c , c E ℝ Find the balance points...

Homework Statement My calculus book gives the following definition of a conservative vector field: A vector field F is called conservative if there exists a differentiable function f such that F=\nablaf. The function f is called the potential function for F. It then gives the...

Hi everyone, Homework Statement Here is the question: The mutual potential energy of a Li+ ion and an I- ion as a function of their separation r is expressed fairly well by the equation U(r)=(-Ke^2/r)+(A/r^10), where the first term arises from the Coulomb interaction, and the values of its...

Homework Statement A 45.0 kg child is in a swing that is attached to ropes 1.90 m long. The acceleration of gravity is 9.81 m/s2 . Find the gravitational potential energy as- sociated with the child relative to the child’s lowest position under the following condi- tions: a) when the ropes are...