Potential energy Definition and 1000 Threads

Homework Statement An electron moves from the positive to the negative terminal of a battery (9V). How much potential energy did it gain or lose? Homework EquationsThe Attempt at a Solution Solving for the amount is basic. That's just qV = 14.4 * 10^-19 J I'm not sure whether it will gain the...

Homework Statement An ice cube is placed on top of an overturned spherical bowl of radius r, as indicated in the figure. If the ice cube slides downward from rest at the top of the bowl, at what angle θdoes it separate from the bowl? In other words, at what angle does the normal force between...

Homework Statement A mass of 235kg is lifted by a winch and an electric motor. The motor does 1800J of work on the mass to raise it to an upper floor. The electric energy needed to complete this task is 160,000J Homework Equations I know the solution but I don't why it is the solution...

Is potential energy gained or lost only in a conservative field, or when work is done against or by conservative forces?

Homework Statement My textbook states that for point charges ##q_1, q_2, ... ,## where distance between ##q_i## and ##q_j## is ##r_{ij},## the total potential energy U is the sum ## U = \dfrac{1}{4\pi\epsilon_0} \sum_{i<j} \dfrac{q_iq_j}{r_{ij}} ## and specifically mentions not to count them...

External field means field does not belong to or is not of the charges present in it,right?So,if there is a system of two point charges and these charges are present in an external field ,it means this external field is not produced by any of the charges present,right? Then there is a derivation...

Consider a system of two charges ## q_1## and ##q_2## separated by distance ##r_1##.This configuration is associated with a potential energy ##U_1##.When the separation is increased to ##r_2##.Potential energy becomes ##U_2## ##dW_E##=##\vec{F}##.##\vec{dr}##...

I know,kinetic energy=##\frac{1}{2}####mv^2## But I saw one other equation it is kinetic energy=##\frac{1}{2}####|P.E|## Then I started looking for in which specific condition is it true?Because I know it is not always applicable .But I could not find that particular condition when it is true.So...

Homework Statement In the following question, in the solution, why is it that when they calculate the gravitational potential energy at point 2 (impact with spring), it is negative? I know that if both the force and displacement act in the same direction, then the work done should be positive...

Homework Statement A 700g block is released from rest at height Ho(initial) above a vertical spring with spring constant k=400 N/m and negligible mass. The block sticks to the spring and momentarily stops after compressing the spring 19.0 cm. How much work is done A) by the block on the spring...

Homework Statement https://s2.lite.msu.edu/res/msu/perl_author/MI3/CH7/IMAGES/MI3_7P32.png The figure shows a potential energy curve for the interaction of two neutral atoms. The two-atom system is in a vibrational state (i.e., a total energy state) indicated by the heavy solid horizontal line...

1. A ball falls to the ground through the air. Is the energy of the air conserved?2. None3. When a ball falls to the ground a transformation of energy occurs. The previously stored potential energy gradually becomes kinetic energy during its fall. The energy conserved in the air is the slight...

Homework Statement One end of a vertical spring of spring constant k = 1900 N/m is attached to the floor. You compress the spring so that it is 2.50 m shorter than its relaxed length, place a 1.00-kg ball on top of the free end, and then release the system att = 0. (All values are measured in...

Homework Statement A bead slides without friction around a loop–the–loop (see figure below). The bead is released from rest at a heighth = 3.60R. (a) What is its speed at point ? (Use the following as necessary: the acceleration due to gravity g, and R.) v = _________________ (b) How large...

I would like to make a pendulum go on moving by a permanent magnet that pushes the pendulum back with a force that is big enough to make it swing back with the same height. Can anyone tell me how much energy could be generated by a pendulum with height is 2 meter and 60 kg, swinging 90 degrees...

I was solving the double pendulum problem via Lagrangian methods but something bothered me quite a lot. (Consider the two bobs are of equal mass and the pendula are of equal length). Then the potential energies are conveniently written as ##V_1=-mgl\cos\theta## and...

Disclaimer: not sure if this is actually the most appropriate forum, but it is a question inspired by my work on a homework question...I'm happy for a moderator to move this to a different forum. (But General Physics states: NO HOMEWORK/COURSEWORK QUESTIONS HERE) 1. Homework Statement Ok...

Homework Statement A solid hemisphere of radius b has its flat surface glued to a horizontal table. A second solid hemisphere of different radius a rests on top of the first one so that the curved surfaces are in contact. The surfaces of the hemispheres are rough (meaning that no slipping occurs...

I understand that ##\Delta U = -W## and that ##\Delta V = \frac {\Delta U}{q}## I don't understand why the example below has "set the change in potential energy equal to the (positive of the) work ...

If I induce vacuum in a glass tube and then I open the lid of the glass tube, air rushes into fill in the vacuum. Can vacuum be regarded as a sort of potential energy, able to exert a force? Can a vacuum tube be considered as a potential storage device for energy, just like a container filled...

Homework Statement I don't understand the answer to part b Homework Equations n/a The Attempt at a Solution The solution guide skipped too many steps. How was this derived? If the 5th charge is in the middle, it will be equidistant (about ##\frac {b\sqrt {2}}{2}##) from each of the...

Homework Statement Homework Equations Gravitational potential energy The Attempt at a Solution Isn't this the solution? So Is <U> = U(r) where a = r? How do I incorporate the ##\frac {1}{\tau}## and the given "useful definite integral" from zero to 2π? Thanks

Hello, In this simulation (link is below) the graph of the potential energy with respect to position U(x) when there is no friction on the ramp looks like the graph of potential energy of Hooke's Law spring U(x)=(1/2)KX^2). For the spring, the negative of the derivative is equal to the...

Homework Statement A child wants to go ride on her sleigh, and she decides to walk up the Big Hill, of height 100 m relative to where she starts. There are two ways up; the steep way, where the slope is 30.0 degrees, and the not-so steep way, where the slope is 15.0 degrees. The...

Homework Statement Evaluate the force corresponding to the potential energy function ##V (r) = \frac{cz}{r^3}##, where ##c## is a constant. Write your answer in vector notation, and also in spherical polars, and verify that it satisfies ##∇∧F = 0##. Homework Equations ##F(x)=-\frac{dU}{dx}##...

Homework Statement An alpha particle is a nucleus of helium. It has twice the charge and four times the mass of the proton. When they were very far away from each other, but headed toward directly each other, a proton and an alpha particle each had an initial speed of 3.6×10−3c, where c is the...

Homework Statement Figure 24-21 shows four pairs of charged particles with identical separations. (a) Rank the pairs according to their electric potential energy (that is, the energy of the two-particle system), greatest (most positive) first. (b) For each pair, if the separation between the...

I have come across the following paragraph from my book "The gravitational force is always attractive .Whereas the electric force is attractive or repulsive acording to whether q0 is negative or positive.Each of the above forces is conservative,so a potential energy is associated with each of...

In my book definition of potential energy difference between two points as the work required to be done by an external force in moving without accelerating charge q from one point to another in electric field of any arbitrary charge configuration.I want to know why without accelerating ?

Homework Statement A proton is composed of three quarks: two "up" quarks, each having charge +2e/3, and one "down" quark, having charge -e/3. Suppose that the three quarks are equidistant from one another. Take the distance to be 3×10-15 m and calculate the potential energy of the subsystem of...

Homework Statement Consider potential field V(ρ, φ, z) = V_0/ρ in free space and cylindrical coordinates. Calculate electrostatic potential energy stored in half cylindrical shell defined by a≤ρ≤b, 0≤φ≤π and 0≤z≤h. Homework Equations W_E=½∫∫∫ρ_vVdV The Attempt at a Solution I have no idea...

Homework Statement Two blocks are hung by a string draped over a pulley, a 1.5-kg block on the left and a 3.0-kg block on the right. The two blocks start out at rest and at the same height. A. What is the change in the gravitational potential energy of the system of blocks and Earth when the...

Homework Statement "Take a PE function U(x), which has an equilibrium point at x=0, and provides a restoring force in that region, and show that a Taylor expansion around that area can be approximated by a SHO PE function for small x." Homework Equations U=.5kx^2...x =...

Hey PF! 1. Homework Statement If I have a pendulum; a vertically hanging rod with (length ##L## and mass ##m##) which can rotate freely about a point ##p## on the upper edge of the rod. Now I fire a bullet (also with mass ##m##) into it (strictly horizontal on the lower end of the rod). I...

Using the potential energy formula -GMm/R^2 I understand that the maximum potential energy is 0. But what is the significance of the potential energy as it approaches negative infinity? I am not sure how exactly to word this, but I cannot seem to grasp the what negative potential energy tells us...

I am calculating the energy transfer in two different formulas and they are giving different results. What could be the reason of this difference? I would be grateful if someone tell me what i am missing here. http://s18.postimg.org/o4tknn77d/potential.jpg

Homework Statement Positive point charge (Q = 8 μC, mass m = 19 g) is fixed at point (9 cm,0). A second identical charge q is constrained to slide on a frictionless wire along the y-axis. Assume: the only force on q is the electrostatic force. If q starts at (0,7 cm) and is released from...

Hey all, question about gravitational potential energy. If an object begins on ground then gains height when it falls then energy it consumes to fall down was the potential created by moving upwards, if an object was created in space, then moves gravitationally towards a celestial body where...

Homework Statement As an electron moved through a region of space, its speed changed from an initial velocity of vi=8114.3 km/s to the final velocity vf=2233.7 km/s. The electric force was the only force acting on the electron. Across what potential difference did the electron travel...

Hi everyone, First, sorry if the question is stupid, I do not have any background in Physics. Just very curious. Potential energy due to gravity is: m * g * h Joules Now, suppose I lift a weight on Moon at a given height. I will have: 1.6 * m * h Joules I maintain it at that height and go to...

My question is, why it's 1/2 [qiVi]? Shouldn't it just be qiVi? Thank you ...

Two charges, q1=-9.4 μC and q2=1.2 nC with masses m1=13.4 gram and m2=2.7 gram were located 8.5 cm from each other. Charge q1 is held in place. We wish to push the 2nd charge q2 as far from the 1st charge as possible. With what initial velocity should charge q2 be pushed to send it all the...

Homework Statement Perform potential energy W of a non-uniform density sphere by density d=d(r) and o(r)=dW/dm. Homework Equations The answer is W=1/2.integral(from 0 to R)(4x3.14xd(r)xo(r)xr^2xdr). The Attempt at a Solution I have solved this by this way: o(r)=-GM(r)/r...

I'm trying to solve an exercise that asks what is the final speed of two positive particles after they are very distants each other. Then I've used the conservation of energy to solve it. The initial energy of the system is the potential energy = Q².k/d The final energy is the 2 knetic energy of...

Homework Statement Why is the gravitational potential energy of a ball a distance r from the center of the Earth negative? Homework Equations U_\text{grav}(r) = - GMm/r [/B] (To me, this makes sense because gravity is an attractive force and bodies will want to minimize the distance between...

Homework Statement Homework Equations W=-ΔU for conservative force. The Attempt at a Solution Let all three forces be conservative. Since particle comes back to where it was, ΔU=0. Hence ΔUAB+ΔUBC+ΔUCA=0 Hence WCA=-WAB-WBC For case A, if both WAB, WBC>0, then WCA<0. Else its greater than...

I was solving for a shape on Earth which has minimum potential energy. i used method of variation calculus. I assumed a function f(x) and rotated it around Y axis. sorry for uploading the problem in word.

Hi, friends! I read that the torque exerced by a uniform electric field ##\mathbf{E}## on a dipole with moment ##\mathbf{p}## is ##\boldsymbol{\tau}=\mathbf{p}\times\mathbf{E}##. Then the book, Gettys' Physics 2, explain that the work made to rotate the dipole around a fixed point is...

Homework Statement Use a computer to calculate numerically the potential energy, per ion, for an ifinite 2D square, ionic crystal with separation a; that is, a plane of equally spaced charges of magnitude e and alternating sign. Homework EquationsThe Attempt at a Solution The closest I can...

So say I had a glass of water on a table ,with the glass filled to the top. The bottom of the glass, the water would have a higher pressure than the top of the glass. This is the concept of hydrostatic pressure etc. But how does GPE fit into all of this? Does the water at the top of the glass...