Conservation of energy Definition and 1000 Threads

Homework Statement A small mirror of area A and mass m is suspended in a vertical plane by a weightless string. A beam of light of intensity I falls normally on the mirror and the string is deflected from the vertical by a very small angle A. Assuming the mirror to be perfectly reflecting, to...

Homework Statement There is a wagon (W) on wheels with a vertical pole of 2m. (mass 20kg) On the top of that pole there is a rope pendulum with an attached mass (M) of 10kg and length 1m. The starting position is a pendulum angle of 60°. No friction taken into account. What is the speed of the...

Homework Statement You hit a golf ball (mass 50g) squarely with the club face from ground level on a flat golf course. The ball leaves the club at an angle of 20 degrees above horizontal and travels 250m before hitting the ground. The force vs time graph below shows the force exerted on the...

I know a similar question has been asked but I'm still kind of stumped. Imagine the Earth on the left and a small mass to it's right separated by some distance h. You are in the frame of reference where the Earth and the small mass are moving to your right at some speed v. So, both the Earth...

Krichhoff's voltage law (kvl) is said to be conservation of energy but i couldn't get a satisfactory explanation for that, i want to say - say, we have a simple circuit consisting of a battery(of emf E) and a resistor(of resistance R), so having connected them by ideal wires, we have electrons...

Krichhoff's voltage law (kvl) is said to be conservation of energy but i couldn't get a satisfactory explanation for that, hence i tried of thinking one but i doubt its validity, my instructors at collage thought of it as something useless , i couldn't understand them ! I think somebody here can...

Homework Statement [/B]Homework Equations [/B] (1) (pink) Is it vertical displacement ? * 4 - 2 (unstretched length of the spring) ? (2) (blue) What does it mean ? * I was thinking that maybe they used The Pythagorean theorem (62+42)=7,2 ≅ 7) but I'm not sure. Besides I don't understand...

Homework Statement One end of a spring is attached to a wall to a block of mass X= 2kg (on a frictionless horizontal table). Another mass M of 150g moving at a speed of 7m/s collides (inelastic). This takes 0.4s to compress the spring to its max compression. I have to find the max force of...

Suppose we have an electric field, and push a proton or electron through it (from rest). We're accelerating it through an electric potential difference of some kind. Why do we apply conservation of energy to the particle-field system to find the speed of the particle? Example: Calculate the...

Hello folks. This is Sandeep. I have many lingering doubts in physics that I am here to get cleared. This has become more of an issue ever since I decided to teach physics to my young nephew. My first question pertains to electromagnetic waves and the conservation of energy. Consider an AC...

Throwing a ball which is (m)kg on the ground If the velocity of the ball just before it reaches the ground is (v)m/s Assume it is a elastic collision The velocity of the ball when it leaves the ground should be (-v)m/s According to conservation of momentum,the ground has a change of...

Assume there is a table with an infinite long wire passing through the centre and few iron pieces lying around the wire on the table. Now I pass current through the wire which creates electro magnetic field due to which all the iron particles get magnetic potential energy. They are attracted...

What is the minimum horizontal force "F" required to hold a simple pendulum (mass "m") with string of length "l" at an angle of 60 degrees with the vertical. [ given answer = mg/√(3) , veracity uncertain ]This at first seemed simple enough, standard mechanics apply, leading to ...

Question:- A bead slides without friction around a loop-the-loop (Please click on the below link for diagram). The bead is released from a height h = 3.50R. (a) What is its speed at point A? (b) How large is the normal force on it if its mass is 5.00 g...

Homework Statement A ball (m=0.7kg) is dropped from a height (h=30m). The air resistance force is given by the formula F=kv^2 where k=0.0228 and v is the ball's speed. The ball bounces after a perfectly elastic collision. Calculate the maximum height the ball reaches after the collision...

I am confused about how the principle of conservation of energy can be used to predict the velocity of a pendulums for any given height and angle. For example, say I use the equation U = -K (potential is equal to kinetic) to solve for the velocity at 15 degrees of a pendulum bob whose wire...

Homework Statement A 1.0 Kg mass is attached to the end of a vertical ideal spring with a force constant of 400 N/m. The mass is set in simple harmonic motion with an amplitude of 10 cm. The speed of the 1.0 kg mass at the equilibrium position is. A. 2 m/s B. 4 m/s C. 20 m/s D. 40 m/s E. 200...

Homework Statement A 250 gram rock is thrown with a speed of 30.0 m/s. It has a speed of 22.5 m/s just before it strikes the ground. Determine the work done by air resistance. There is also a diagram which yields more information. The rocks path is horizontal and it strikes the corner of a...

Homework Statement So I'm trying to prove to myself that energy is conserved in the case of magnetism. Here is the set up that I'm using to get that understanding (attached image). Just to be clear the arrows represent the current lines and I am calculating a gain in PE because if I release...

Homework Statement [/B] Three masses are positioned on a frictionless surface, as shown. Initially, mass m1 (1.0 kg) moves with a velocity of 2.0 m/s to the right, mass m2 (2.0 kg) is at rest, and mass m3 (3.0 kg) moves to the left with a velocity of 0.50 m/s. First, mass m1 collides...

Hello, I have found an issue in a simple classical electrodynamics problem that I have not been able to explain, so I’m writing this post hopping to find some answer to it. The problem is this: we have two charged particles with the same charge but different sign, one is massive and I will...

Everybody experiments fatigue holding a weight, and almost everybody knows that points of applications of the involved forces don't move. We also know that we cannot use the standard equation of the conservation of energy ( ΔK + ΔU = Wext ) because the system (Body+weight) is composed by...

Homework Statement I was given a chart to figure out the different momentum and kinetic energies of different collisions (elastic and inelastic) and in the lab he posed the question "Calculate the percent elasticity for each of the collisions." Homework Equations conservation of momentum...

Homework Statement A photon with of 13600eV energy interacts with a hydrogen atom at rest and ejects the electron (photoelectrically) in the direction in which the photon was travelling. If 13.6 eV is required to eject the electron, find the speed of the photoelectron and the momentum and...

If quantum foam particles can exist long enough to interact with other close particles before returning to the vacuum, doesn't this introduce kinetic energy to a system that previously didn't have it before? Does this perhaps imply that a system (such as the universe) cannot actually be isolated...

So, this is something I've never understood in detail. If an excited system decays and emits a photon, the lifetime of the decay will broaden the spectrum of the photon right? Basically just a Fourier transform of the "shape" of the emission in time to get the frequency components of the...

Question: A streetcar is freely coasting (no friction) around a large circular track. It is then switched to a small circular track. When coasting on the smaller circle its speed is: a) greater b) less c) unchanged Relevant Formulas: w = v/r KE = 1/2mv2 My teacher said the normal force from...

If an object is dropped from height, h, then gravitational energy is E = mgh, but kinetic energy when object hits the ground is E=(1/2)mv^2. Conservation of energy states that E(g)=E(k). Why does kinetic energy not depend on height object was dropped?

Homework Statement Prove kinetic energy is relationship between mass and velocity using E(g)=mgh (no calculus, momentum, kinematics). Homework Equations gravitational energy: E=mgh kinetic energy: E=(1/2)mv^2 The Attempt at a Solution I know it can be derived using the gravitational energy...

Homework Statement Homework Equations Conservation of Energy (Potential + Kinetic = Potential + Kinetic) The Attempt at a Solution At the start of the ramp, potential energy is mgh (gravitational potential) and kinetic is 0, since it's not moving. At the bottom of the loop, potential...

Homework Statement A skier starts at the top of a friction less hill. You have 4 different runs, they have different difficulties. So I am assuming they are at different inclines. 1) longest route, not so steep 2) medium length, little steeper 3) shorter more steep 4) straight path, and very...

Homework Statement A girl of mass m1=60 kilograms springs from a trampoline with an initial upward velocity of vi=8.0meters per second. At height h=2.0 meters above the trampoline, the girl grabs a box of mass m2=15 kilograms. What is the speed of the girl after she grabs the box? Homework...

Homework Statement Hello everyone, I was hoping I could get someone to help me out please. I am having great difficulty with my thermodynamics course and I have an assignment due tomorrow. I need to reduce the conservation of energy formula so that it applies to Earth so I can work on my...

Homework Statement Two masses are connected by a string that hangs over a frictionless pulley with mass 8kg, radius .25m, and moment of inertia .5mr^2. One mass lays on the ground and has mass 15kg. The other mass is 22.5 kg and is 2.75 m above the ground. Use conservation of energy to...

Homework Statement A 1Kg rocket is fired off. The engine provides a thrust of 18 Newtons for 20 meters. What is the maximum height achieved by the rocket? Assume no loss of mass and no friction. Gravity=9.8m/s^2 Homework Equations Work=Force x distance Force=Mass x acceleration(or gravity)...

Reading "Atmospheric Thermodynamics" I'm stumped almost as soon as I've started. I've probably bitten off more than I can chew and this also might even be more of a math question than a physics one but where I'm stuck is where they "simplify" from: mv . dv/dt = -mgv . ez (where ez is a unit...

I have a conservation of energy question I’ve asked about elsewhere but I didn’t get a fully satisfying answer. I hoping someone here can help. TIAhttp://wedgecircles.com/images/384_newmpe01.gifSay you have two magnetically aligned magnets close to one another but some distance apart. There...

Homework Statement A mass is attached to a spring (on a wall) of constant 100 N/m. The mass is 1 kg. The mass has an initial position of 3 m from the equilibrium position and is given an initial velocity of 5 m/s. Find the period and amplitude of oscillations. Homework Equations [/B] Period...

Consider a parallel plate capacitor in vacuum, we hold a test charge below one plate and release it at some point in time, we observe that the charge is accelerating towards the other plate, that is the charge is gaining kinetic energy. My question is how does the loss of energy from the...

Hey, Say we have an object released at rest, separated by a certain distance..blah, blah, blah. When we use conservation of energy here, the kinetic energy would have a initial velocity right? So, K1+U1=K2+U2 assuming the object eventually comes to a rest...so U1 = 0, K2 = 0, so we would have...

Homework Statement One of the three types of radioactive decay is "β decay", during which protons decay into neutrons or viceversa, emitting either electrons (β) or positrons (β+) at high velocity as a result. In one experiment, a β source and β+ source are placed 10 cm apart from each other...

Homework Statement A 2.0 kg ball moving with a speed of 3.0 m/s hits, elastically, an identical stationary ball as shown. If the first ball moves away with angle 30° to the original path, determine a. the speed of the first ball after the collision. b. the speed and direction of the second...

I have a question about conservation of energy... So, I have a question about conservation of energy. I just want a detailed example of the path of the energy in some regular scenarios and the reach of it. For example... When playing pool, the cue ball is shot at a stationary 8 ball. The cue...

If I had a block that I pushed with a force F along a horizontal path and then removed the force before an incline, would the angle of the incline matter on how far above the ground the block would travel? I am assuming a frictionless surface.

Homework Statement You get a new job working for a railroad company and your first task is to work out the refuelling strategy and fuel budget for the new trains. Your company has recently purchased charger locomotives which have a mass of 120,000kg and a top speed of 210km/h and run on diesel...

Homework Statement Newton's cradle. Each ball is 50 g. First ball is raised to 3.0 cm, and the final ball reaches 2.6 cm after the collision. 1) Use the law of conservation of energy to calculate its velocity before impact. 2) Use the law of conservation of momentum to determine the velocity of...

Imagine a ball rolling down a hill or inclined plane without slipping from a particular height. The conservation of energy law says that the final energy remains the same as the initial energy. But, when a ball is rolling without slipping, there must be a friction. So, what I think is E = E' mgh...

Homework Statement A spring of negligible mass has force constant k = 1800N/m . You place the spring vertically with one end on the floor. You then drop a book of mass 1.20kg onto it from a height of 0.500m above the top of the spring. Find the maximum distance the spring will be compressed...

Imagine bringing a toaster and a slice of bread into space. After doing so, we were to toast the slice, measure the temperature after toasted, then chuck the piece of toast out into space quickly before too much heat transfers. After a week goes by, we find the piece of toast and bring it back...

Homework Statement http://www.sumoware.com/images/temp/xzmomoeqpspoqxcq.png A block with mass m is static at first at the height of 2R (see picture above) and then slides without friction. a) Determine where the block leaves the track b) Determine the maximum height which the block reaches...