Conservation of energy Definition and 1000 Threads

Homework Statement To form a pendulum, a 0.092 kg ball is attached to one end of a rod of length 0.62 m and negligible mass, and the other end of the rod is mounted on a pivot. The rod is rotated until it is straight up, and then it is released from rest so that it swings down around the...

I wanted to check some concepts in collisions because I'm a little bit confused. In a real-world collision (Where everything applies, friction and so on) conservation of momentum doesn't really apply because there is friction, which is an external force. 1)That is the only reason momentum...

Homework Statement A 105 kg acrobat jumps up off a platform at a velocity of 2.50 m/s and lands on a teeter-totter 3.00 m below, where another acrobat is waiting. If the waiting acrobat has a mass of 62.5 kg, how high does she get? Homework Equations KE=(1/2)mv^2 PEg= mgh The...

Homework Statement Suppose there is a block attached to a spring with spring constant k. The block is pushed so that it compresses the spring a distance x_1. The block is released and slides without friction up a ramp, coming to a maximum height h_1 above the ground. Suppose we compressed the...

I know that's impossible, so please help me! Let there be a body rotating about its axis, with a moment of inertia I and an angular velcity w. The angular momentum of the system is L = Iw. Now, if the radius of the body change, its moment of inertia will also change. Let the new moment of...

Homework Statement 1.A rocket at the surface of the Earth is launched with a speed of 2500m/s. What is the orbit that the rocket will achieve? 2.A meteorite traveling at 3500m/s approaches Earth from outer space. With what speed will the meteorite hit the surface of Earth? 3.Also, in...

Homework Statement A standing wave is produced by small transverse oscillations of one end of a taught string stretched between an oscillator and a fixed point. The frequency of oscillation is adjusted to be resonant at the third harmonic. The amplitude of the string's viabration is very...

Homework Statement Gus is at end of rope. He needs to reach roof. His friend fires cannon ball horizontally hitting Gus and get stuck in belt. Find minimum speed of cannon ball for Gus to reach roof. 50m is rope. 99kg is Gus. 1kg is ball. 45° angle in diagram Homework Equations...

Homework Statement Homework Equations mgh=1/2mv^2 The Attempt at a Solution 7.1) 200*1000=200000kg 7.2) Must I use mgh? They asked for kinetic energy but energy is conserved so: 200000*9.8*150 = 2.9*10^8 J 7.3) Ep=Ek 2.9*10^8=1/2*200000*v^2 v=53.8 m.s 7.4) 85% of 2.9*10^8 = 2.5*10^8 J...

A tiny sphere of mass 7.70 µg and charge −2.80 nC is initially at a distance of 1.74 µm from a fixed charge of +9.25 nC. (a) If the 7.70-µg sphere is released from rest, find its kinetic energy when it is 0.500 µm from the fixed charge. (b) If the 7.70-µg sphere is released from rest, find...

Homework Statement see the 2 image attachments. Homework Equations law of conservation of energy Fs = -kx Eg = mgh Ek = 1/2mv^2 Es = 1/2kx^2 The Attempt at a Solution i have no idea.

since energy absorbed by a BH is no longer available to the universe, why is that not a violation of the principle of conservation of energy?

Homework Statement A cooking vessel on a slow burner contains 11.0 kg of water and an unknown mass of ice in equilibrium at 0°C at time t = 0. The temperature of the mixture is measured at various times. During the first 50.0 min, the mixture remains at 0°C. From 50.0 min to 60.0 min, the...

Homework Statement Here's the problem : http://www.diigo.com/item/image/2sb3i/wonu Homework Equations Ei = Ef The Attempt at a Solution The surface between A and B is frictionless : Ei = Ef KA + UA = KB + UB mghA = 1/2 mvB2 vB2 = 2ghA = 2*9.8*3 = 58.8 m/s The surface...

Allover the web i am only seeing a statement similar to this: "Pair production is not possible in vaccum, 3rd particle is needed so that conservation of momentum holds." Well no one out of many writers shows, how to prove this matematically. So this is what interests me here. First i wanted...

Hello, We're studying sound waves in Physics and my instructor did a quick demo showing resonance with a tuning fork. He showed that when a tuning fork is struck and then connected to a resonating cavity, the sound is substantially amplified. I understand that resonance arises due to sound waves...

Homework Statement So I have a ball rolling down a ramp structure from rest and up a curve,to launch out at 15 degrees. The ball lands 100cm away in a hole 0.05cm deep. The height in which it comes out of the ramp is 0.05cm high angle at which ball launches out = 15 degrees above horiontal...

Homework Statement A particle of mass 0.400 kg is shot from P . The particle has an initial velocity vi with the horizontal component of 30 m/s. The particle rises to a maximum height of 20 m above P. Using the law of conservation of energy, determine : (a) the vertical component of vi (b)...

My problem is with where the initial height being R - R cos theta. I don't really get where that came from. any hints on where i could look to find the answer or suggestions on how to start are greatly appreciated. nevermind i figured it out

Understanding conservation of energy during generation of entanglement. In the experiment for generation of entangled pair of photons via SPDC Single photons are struck on a BBO crystal. In about 1 in a trillion of such collisions, two photons emerge. Questions: 1. Is the...

Hi guys, Can someone help explain something to me. In a situation of an asteroid heading straight towards the Earth, I'm trying to understand where the energy comes and goes (using just gravitational potential energy and kinetic energy). Consider the energy of the asteriod some distance...

When a particle is in superposition of energy eigenstates and has a probability of being found in either state, what does that say about the energy of the particle and conservation of energy. What I mean is, since the energy eigenstates have different energy values, where's the rest of the...

Homework Statement A 5.00-kg block is set into motion up an inclined plane with an initial speed of 8.00 m/s. The block comes to rest after traveling 3.00m along the plane, which is inclined at an angle of 30° to the horizontal. For this motion, find the change in the block's kinetic energy...

Homework Statement if a basketball of mass=5kg is dropped from a height of 3 cm hits the ground and it compresses 0.015m then what is the spring constant

Homework Statement 1. A photon with an initial energy of 33eV collides with an electron. If the speed of the electron after the collision is 4.56*10^5m/s the final energy of the photon is? [32.4eV] 2. Photons that compose a monochromatic beam of light each have a momentum of 1.50*10^-28...

Homework Statement A 50 kg pole vaulter running at 9.5 m/s vaults over the bar. If the vaulter's horizontal component of velocity over the bar is 1.3 m/s, and 200 J of energy is lost due to the friction in the pole, how high did the vaulter jump? Homework Equations K1+U1= K2+U2+Wf...

Homework Statement I'm devising a lab to find/prove the conservation of energy through one of Newton's laws. I can substitute variables when do the lab, but I need to design it first before I assign variables or data.Homework Equations K.E.(initial) + P.E(initial) = K.E.(final) + P.E.(final) X...

Hi, Homework Statement I have three elementary questions and would appreciate feedback on my attempt at answering them. Thanks in advance! (1) Will the laws of conservation of energy be accurately preserved in the lab? (2) When pushing a cart across a surface, how can energy losses...

Homework Statement http://imgur.com/ZGvC1 At what angle does the cart fly off of the track? No other information is provided Homework Equations I know that energy is always conserved (total energy before = total energy afterwards). The Attempt at a Solution Equation for...

Homework Statement I'm having some trouble understanding "conceptually" the following problem (example 6.18 in Kleppner and Kolenkow.) A stick, initially upright, starts falling: find the speed of the center of mass as a function of position. Homework Equations Work-KE thm. for a rigid...

Homework Statement A bomb explodes into three pieces, two have an equal mass and fly off at 60 degress to one another with the speed of 100 m/s. The third piece has three times the mass of each of the other pieces. Find the direction and magnitude of the third piece immediatly after the...

Homework Statement A 0.75-kg block slides on a rough horizontal table top. Just before it hits a horizontal ideal spring its speed is 3.5m/s. It compresses the spring 5.7 cm before coming to rest. If the spring constant is 1200N/m, the internal energy of the block and the table top must...

Hi Ive recently carried out an experiment where different masses are hung from a string and then dropped from the same height. The other end of the string is wrapped around the axle of a flywheel and when the mass hits the ground, the time for ten revolutions of the flywheel is calculated to...

Homework Statement A dynamics cart 1 ahs a mass of 1.8 kg and is moving with a velocity of 4.0 m/s[right] along a frictionless track. Dynamics cart 2 has a mass of 2.2 kg and is moving at 6.0 m/s[left]. The carts collide in a head-on elastic collision cushioned by a spring with spring constant...

Homework Statement Homework Equations T1 + V1 = T2 + V2 T = kinetic energy V = potential energy The Attempt at a Solution I am only confused about how to get T2. Here is how the answer key gets T2: I don't get why Va = Vb = 0. The wheels have some velocity so it doesn't...

Homework Statement Alright so I am confused about why the solution does not include the kinetic energy due to rotational energy from I_g2 as indicated in red in the following image. I don't understand why they would neglect it... I calculated the value and it makes a big difference.

Quick Question on Conservation of Energy! :( #1. For this one, I did a) W = ½kx² = ½*410*.053² = 0.5758 J b) V = √[2W/m] = √[2*.5758/2.00] = 0.7588 m/s Are those right? If so, can you help me solve Number 3 and 7 real quick! #3. #7.

Homework Statement A spring, having a force constant of 6.0x102 N/m, is held in a vertical position and compressed 0.30m. A 5.0 kg mass is then placed on top of the spring. THe mass is then releases. Neglecting air resistance and the mass of the spring The Attempt at a Solution Ek1 = Ek2...

Homework Statement a hockey player of mass 80 kg was skating at a velocity of 7.5 m/s [E 20 S] when he accidentally hit a linesman who was just standing on the ice. The mass of the linesman is 90 kg and his velocity after the collision was 3 m/s [ N 30 E]. Find the velocity of the hockey...

Two children are playing a game in which the try to hit a small box on the floor with a marble fired from a spring loaded gun mounted on a table. The target box is horizontal distance D=2.20 m from the edge of the table. Bobby compresses the spring 0.011m but the center of the marble falls 0.27...

Homework Statement A very long, thin straight line of charge has a constant charge density of 2.0pC/cm. An electron is initially 1.0cm from the line and moving away with a speed of 1000km/s. How far does the electron go before it comes back? Homework Equations ΔU = ΔV*q ΔKE + ΔU = 0...

Hi, I'm new to this forum. So I do not understand how, in an inelastic system, momentum is conserved. Consider this problem: Tarzan swings from a branch 4 meters up and picks up jane how far can he swing up the other side? He weighs 100kg and is standing still on the branch. He jumps...

Suppose we have a rod standing vertically and then slightly disturbed so it begins to fall. After it falls through some height or angle assuming a clockwise rotational fall I can see that the left end is sliding on the surface ( for simplicity I'm ignoring friction ) horizontally. Here I assume...

I don't know if I'm setting up the energies correctly. 1. Two objects are connected by a light string passing over a light, frictionless pulley. The object of mass m1=5.00kg is released from rest at a height h=4m above the table. Using the isolated system model, (a) determine the speed of the...

Homework Statement A comet is traveling towards the earth. The comet has a mass of 4.80E+12 kg and a radius of 385 m. The comet is traveling with a speed of 19 km/s and spinning with a period of 0.12 seconds when its center is a distance 1.88E+7 m away from the center of the earth. The comet...

[b]1.2. If a ball and string pendulum is pulled and lifted to a height = 10 cm and the length of the string is 1 m what will be the value of h when the string makes an angle of 90 degree with the vertical? Please ignore the 0.5 m it should be a h = 10 cm or 0.1 m the diagram is to provide a...

Homework Statement A block of mass m=2.00 kg is attached to a spring of force constant κ=500 N/M. the block is pulled to a position xi=.05m and released from rest. Find the speed the block has as it has passed equilibrium. Assume frictionless. Homework Equations ΔEsystem=ƩT(transfer)...

There MUST be steps to solving problems dealing with Conservation of Energy! No? There just HAS to be... like Step 1) What does the problem give you... Step 2) Was does the law of Conservation of Energy state Etc Etc... For example...16. A 66.0-kg person throws a 0.0480-kg snowball forward...

Homework Statement A 785-gram metal block is placed on a level table that is 1.6 m high. It is connected to a horizontal spring whose force constant is 3000 N/m. The block is pushed against the spring, compressing it by 0.100 m, and released. It slides along the table and goes off of the...

A child whose weight is 267 N slides down a 6.10 m playground slide that makes an angle of 20.0° with the horizontal. The coefficient of kinetic friction between slide and child is 0.10. (a) How much energy is transferred to thermal energy? (b) If she starts at the top with a speed of 0.534...