Energy is a quantity which gives an overview of the amount of work doable by the system.

learn more… | top users | synonyms

0
votes
0answers
60 views

First-order pertubation theory

I'm having some trouble figuring this out, so I was hoping someone could help. I need to show that the first-order pertubation of the ground state energy is not changed by the pertubation $H'$, given ...
0
votes
0answers
50 views

Bass and Treble-Car Steroes

In a car which phenomenon, diffraction or the resonant frequency of the car, lends itself more to the ability of bass to go farther? Related Answer: Why do bass tones travel through walls?
0
votes
0answers
282 views

How does the volume change affect an adiabatic process?

A gas consisting of rigid diatomic molecules was initially under standard conditions. Then the gas was compressed adiabatically, 5 times the original volume. Find the mean KE of rotating molecules ...
0
votes
1answer
82 views

Pendulum system: how is derived the output as Energy?

Good day to everyone, I want to understand in which way the "Energy equation" is been implemented to this pendulum system. $x_1(t)$: The angular position of the mass $x_2(t)$: The angular velocity ...
0
votes
0answers
54 views

Time reversed laser

Recently, I read an article on time reversed laser. I don't know why they call it a time reversed. I have a doubt that why they use two laser in the device. And what is an anti-laser? The device ...
0
votes
0answers
411 views

Nuclear reaction: creation of deuterium

A proton p collides with a neutron(at rest) n at relatively low-energies and creates a 'deuterium-core' d: $$p+n->d+\gamma$$ Find the wavelength for the photon as a function of the proton's ...
0
votes
1answer
1k views

Work being done without distance

I have this issue: If you push a 40.0 kg crate at a constant speed of 1.40 m/s across a horizontal floor (µk=0.25 ), at what rate (a) is work being done on the crate by you and (b) is the energy ...
0
votes
0answers
39 views

Elastic Collision Between Two Objects [duplicate]

Possible Duplicate: Elastic Collision And Momentum I've already asked this question, Elastic Collision And Momentum, but I didn't find the answer particularly helpful--sorry, I don't mean ...
0
votes
1answer
661 views

Momentum And Energy Problem

The information to the question is, "A $59.0~kg$ boy and his $38.0~kg$ sister, both wearing roller blades, face each other at rest. The girl pushes the boy hard, sending him backward with a velocity ...
0
votes
0answers
59 views

Energy can't be created or destoryed? [duplicate]

Possible Duplicate: Conservation law of energy and Big Bang? If energy can't be created or destroyed then how did the big bang create energy? and if energy can't be created then does that ...
0
votes
1answer
324 views

Faraday's law and superconductivity

According to Faraday's law of induction, volts = -Number of coils in a solenoid * change in strength of magnet / change in time. This doesn't take into account distance or speed, only time. If amps = ...
0
votes
0answers
610 views

Error Analysis, Change in momentum, Kinetic Energy

If momentum of an object is increased by 10%,then its kinetic energy will be increased by? Well, I don't need the solution logically by calculating the change in Kinetic Energy etc, but my question ...
0
votes
0answers
61 views

Taylor approximation of e(v) [closed]

Relativistic mass $\displaystyle m(v)=\frac{m_o}{\sqrt{(1-(v/c)^2}}$ $m_o$ = mass of object measured at rest $c$ = speed of light ($3\times 10^8\;m/s$) $v$ = speed If the total relativistic energy ...
0
votes
1answer
144 views

Proportion of energy compared to mass in universe

In Wikipedia (http://en.wikipedia.org/wiki/Dark_matter), there is a picture that shows us the proportion of matter and energy in the current universe - CMB. It seems to suggest there is nothing that ...
0
votes
1answer
6k views

Water Electrolysis Calculations

From Wikipedia (http://en.wikipedia.org/wiki/Water_electrolysis#Efficiency): The electrolysis of water requires a minimum of 237.13 kJ of electrical energy input to dissociate each mole. Each ...
0
votes
0answers
141 views

2 streams going into an engine and 2 come out. Find the enthalpy?

Problem: Steam supply to an engine is made of two streams that mix before entering the engine. Stream 1 flows at a $.01\frac{kg}{s}$ with an enthalpy of $2952\frac{kJ}{kg}$ and a velocity of ...
0
votes
0answers
84 views

When will the moon fall down? [duplicate]

Possible Duplicate: Are tidal power plants slowing down Earth's rotation? I've heard that there are turbines converting energy from tidal waves. Tidal waves are created by the moon's ...
0
votes
2answers
3k views

How to calculate fuel consumption of car (mpg) from speed and accleration knowing mass, drag coeff and rolling resistance?

How can I calculate the current (instantaneous) mpg of my car if I know the speed and acceleration of the car? From reading various answers for the "car going level or up/down hill" question asked ...
0
votes
2answers
61 views

How to find height, when given the velocity at that location, starting height, and mass of object? [closed]

The question: A roller coaster is 100m above the ground, and weighs 1000kg. At one point of the roller-coaster-ride, the velocity is 28 m/s. What is the height of the roller-coaster at that ...
0
votes
1answer
96 views

What happens to matter when in a thermodynamic equilibrium?

I am trying to gain a better understanding of thermodynamic equilibrium. Here's what (I think) I know: If a system is in Thermal, Radiative, Chemical, and Mechanical Equilibrium, then it is in ...
-1
votes
2answers
180 views

Do you need energy to exert a force?

Is force dependent or independent of energy?
-1
votes
1answer
498 views

Power generator powered exclusively by gravity is possible? [closed]

According to this site, it seems so. Power generator powered exclusively by gravity:
-1
votes
3answers
107 views

Is it possible to be changed Energy Unit in future or it is strict reality in nature?

Could you pease tell me why energy unit must be $Energy=Mass . \frac{Distance^2} {Time^2}$? (I tried to write general form of Energy unit) What is the strong proof of that unit? Does it just depend ...
-1
votes
2answers
143 views

Energy required to reach 1 wavelength [closed]

I was curious if there was a forumla to find the energy required to reach 1 wavelength in a given substance. (or a vacumn if that's too hard). I am also wondering if this number can tell us anything ...
-1
votes
3answers
2k views

Is kinetic energy a scalar? [closed]

Is it correct to say that kinetic energy is a scalar?
-1
votes
1answer
137 views

How much energy is consumed by a aircraft to maintain a speed of sound? [closed]

Let's assume that the aircraft is 1000kg and it is flying in a air density of 1.225kg/m^3 at the speed of sound in air. Just how much energy does it require per second to maintain flying at this ...
-1
votes
2answers
608 views

How we can find the kinetic energy? [closed]

A solid disk of mass m is rolling along a surface its center has velocity v what is the kinetic energy of disk?I cannot solve the problem,
-1
votes
2answers
205 views

Show that the energy levels of a particle in a specific potential are $E_n=(n+\frac{1}{2})h\omega-\frac{1}{2}\frac{F^2}{m\omega^2}$ [closed]

A particle of mass m moves on the x-axis under the influence of the potential $$V(x)=\frac{1}{2}m\omega^2x^2+Fx$$ Can anyone help me, using Schrödinger's equation in one dimension that the energy ...
-1
votes
1answer
43 views

how to use the energy work kinetic theorem [closed]

A single force acts on a $3.4~\text{kg}$ particle-like object in such a way that the position of the object as a function of time is given by $x = 4.2t - 2.1t^2 + 2.5t^3$, with $x$ in meters & $t$ ...
-1
votes
1answer
81 views

Whether nuclear physics or nuclear engineering is suitable for doing research in nuclear fusion? [closed]

I want to do research in making nuclear fusion sustainable for electrical energy production , which field I should choose? and it is worth doing research in fusion now, since many of them are saying ...
-1
votes
2answers
557 views

Calculate the electric potential energy stored in a capacitor [closed]

Calculate the electric potential energy stored in a capacitor that stores 3.40 x 10^-10 C of charge at 20.0v I am lost. I am scared.
-1
votes
2answers
88 views

Time difference in transmission of AC and DC

Is there any time difference while considering the transmission of AC and DC ? Is either one of them faster than the other one in terms of transmission of energy/power from one point to another? I ...
-1
votes
1answer
98 views

Determine KE of electron given momentum & mass [closed]

Some info: wavelength of electron: $2.78 \times 10^{-10}$ momentum of electron: $2.38 \times 10^{-24}$ Determine KE of electron. In a provided hint: $KE = \frac{p^2}{2m}$. So I have: $$KE = ...
-1
votes
2answers
68 views

Changing Direction in a Vaccum [closed]

If a mass of one kilogram is traveling at one meter per second at 90 degrees, how much energy is required to get it to travel going 180 Degrees?
-1
votes
2answers
162 views

Why is the work positive here?

Problem http://apcentral.collegeboard.com/apc/public/repository/ap11_frq_physics_b_formb.pdf Please refer to question 1f Solutions ...
-1
votes
1answer
190 views

Spring launches a mass on an incline plane with friction, find the height [closed]

So I've calculated the answer to this problem, but my answer is different from my book's, so I'm trying to find the error. A spring with coefficient $k=600N/m$ launches a mass of $1.2kg$ from an ...
-1
votes
1answer
26 views

Calculate amount of energy based on height of object

How can you calculate the amount of energy an object produces that falls from a particular height? Or water. In an eg i would like to know how can you calculate the amount of electricity water can ...
-1
votes
1answer
27 views

Is watt unit depended on turbine speed

I'm new to electronics. I have a doubt. That is... Is watt unit depended on speed of turbine ? In my mind When turbine rotates fast the power in increase. Is it right ? Please help me. Thanks for ...
-1
votes
1answer
32 views

Atoms and their bonds in an explosion

I was watching a video and when the car did blow up I asked to me... what happens with the atoms and their bonds when an object blows up of this way? what is the behavior of the atoms and their bonds ...
-1
votes
1answer
44 views

Total energy of a body following circular motion

I learned that when a body rotates, its total energy is, $$energy=\left(\frac12\right)mv^2 + \left(\frac12\right)I\omega^2 $$ However, if an astronomical object is orbiting around the earth, is ...
-1
votes
3answers
291 views

Explain internal energy and enthalpy

Internal energy and enthalpy. I am finding it hard to distinguish between the two. Confused. Can someone explain me the two terms and difference between them? I tried learning from wikipedia but it ...
-1
votes
1answer
638 views

Kinetic energy of a rotating rod [closed]

I have no idea where to even begin with this... Find the kinetic energy of a record of uniform density, mass 50 gm and radius 10 cm rotating at 33 and 1/3 revolutions per minute. Normally I would ...
-1
votes
1answer
105 views

What lifting mechanism is likely to have the best energy recovery ratio? [closed]

Suppose I was designing an apparatus which needed to lift 250kg 5cm high, hold it there for a few seconds, and then lower the object back to the original height. Such a process would need to be ...
-1
votes
3answers
787 views

From knowing just the change in kinetic energy, can we find the friction force and engine power?

I understand this topic well enough to get all the task done because they aren't very creative. But for my exam I think I should have this clear. During the acceleration the force from the engine is ...
-1
votes
2answers
1k views

Formula for getting energy required to accelerate to a certain speed?

I am curious how many newtons it takes to accelerate an object with a given coefficient of drag, reference area, weight, and air pressure? I know this may sound like a simple equation but I have no ...
-1
votes
1answer
28 views

is it possible to change the energy of a waveform like radio wave & turn it into microwave?

In the electromagnetic spectrum, the differences between all waveforms are the "frequency" & energy of the waveform. We are able to modify both of these parameters. So, is it possible to change ...
-1
votes
1answer
78 views

Is it feasible to transfer energy from power stations to communities via photons instead of electrons?

Electrical wires are relatively inefficient in transferring energy--especially when the place of production is quite far from communities. Would it be possible to transfer that energy via photons? I ...
-1
votes
1answer
29 views

Averaging energy density

Let we define energy density by, $$E= a^2 \cos2 t +b^2 \sin2 t+ c^2 \cos 3t$$ where, $E=$ total energy, $a,b,c =$constants, and $t$ is the time. I'm confused from someone's statement that ` There ...
-1
votes
1answer
170 views

What energy changes take place when you operate a jet-ski?

What energy changes take place when you operate a jet-ski?
-1
votes
1answer
86 views

Gravitational potential energy

Consider two places next to each other: Place 1, where there is a gravitational field whereas Place 2 - there's no field. Now if we lifted a box in place 1, it gains potential energy. Then, we move ...