Energy conversion Definition and 81 Threads

We wrap a light, flexible cable around a thin-walled, hollow cylinder with mass M and radius R. The cylinder is attached to the axle by spokes of a negligible moment of inertia.The cylinder rotates with negligible friction about a stationary horizontal axis. We tie the free end of the cable to a...

as mass is converted to energy in stars, is universe losing total mass?

Homework Statement At what height should a parachute be opened so the final speed is 5.00 m/s. (The parachuter is 80.0 kg. He jumps off a balloon at 1,000 m. The total retarding force on the man is constant at 50.0 N with the parachute closed and constant at 3,600 N with the parachute open.)...

Homework Statement If the calorific value of wood is 16 MJ/kg and a match weights approximately 0.17 g, then (a) how much energy (in joules) is released by burning the wooden part of a single match? If all of this energy were applied to do work to lift a 60 kg human vertically, against...

Lets say we had a twister, below it there's a lit candle, after a while the blades of the twister move. I know its because the air around the flame is heated and so the air rises. But can we say heat energy converts to kinetic energy in this situation. Becuause its not becuz the air got heated...

Lets say we have a frame of reference moving at, say, 10% speed of light. In it is a nuclear reactor (fusion or fission etc) that can be used to convert tiny amounts of mass into energy. Since the reactor is moving at, say, 10% the speed of light, the mass of the nuclear material would...

The excuse given to why energy conversion efficiency even exists, is because that some of the energy is converted to heat. Then how come in electric HEATERS not all the energy is converted to heat? To what does the rest of those 5% is being converted to...

hot water! (energy conversion) Hello colleagues I´m new here and I'm from delicias, Chihuahua, Mexico and the reason of my post is that I want to do something with the water that is discarded of the mine of Naica, Chihuahua because this water from the mine has a lot of energy, I mean the water...

As lighting decorations, EL wires that use an alternating current to make a phosphorous material radiate light are said to be very efficient and generate little heat. But what exactly is the energy conversion efficiency of such a device expressed as the ratio of output radiative power divided by...

Hello! I was wondering if someone could take a look at this idea and tell me if there is something wrong with it: In attempting to shut down every part of a hypothetical spacecraft except some sort of highly insulated crew pod, the total amount of heat produced over a period of time is...

Hi all, Dose kwh/m2 and mwh/cm2 and watt/m2 equal? if not what are the relationship between them? How can convert between them?? Thanks in advance Smile_Face :)

I have a doubt regarding mass to energy conversion. Suppose I consume m1 kg of food at beginning of a day. Will it be equal to the mass of solid and liquid wastes out of my body on that day (say m2) and increase in mass of my body (say m3) and added to energy gained by me from that food (Eg)...

New here. If this isn't the right forum for the question excuse me. I saw a science demonstration of converting heat to mechanical energy. it was a circular rim supported on an axle by rubber band spokes, kind of like a bicycle wheel but with rubber bands instead of metal spokes. kind a...

When a helium balloon rises from rest, it gains Ep, at the same time, it gains Ek. So where does these energy come from? My guess would be due to density differential, the balloon will rise and this will displace the air molecules which will fall to take the place of the balloon. This reduction...

I don't know basically anything about nuclear physics, but I do know that mass can be converted to energy. Nuclear reactions, anti-matter, etc. But can energy be converted into mass? If so, where would this happen?

Homework Statement A soft clay block is suspended so as to form a so-called ballistic pendulum. A bullet is fired point-blank into the block, imbedding itself therein and raising the latter to a height h. Derive an expression for the percentage of the kinetic energy converted into internal...

Homework Statement A 60 kg hiker wishes to climb to the summit of Mt. Ogden , an ascent of 1500 m. a) Assuming that she is 25 % efficient at converting chemical energy from food into mechanical work, and that essentially all the mechanical work is used to climb vertically , roughly how many...

How energy conversion takes place in dc machines (motor or generator)

How back emf helps in energy conversion in a motor? hello, I am an engineering student and during the past few days i was searching on the net to clarify my doubts on "motors".So i came across an article and on reading one part of it a doubt arosed in my mind. Q1) "To take a practical...

Hi, I was wondeing if anyone could help me out here. What form of energy can most efficiently be converted to electrical energy (by current means)? Cris

The problem is: The sun is 1.5x10^11 meters from the earth. Energy from the sun is received at the Earth's surface at the rate of 1.4 kilowatts per square meter. I'm trying to find two answers: 1. This energy flux from the Sun falls on a pond of water 100 square meters in area and 0.1 meter in...

a) A 15g bullet is fired at 840m/s into a ballistic pendulum consisting of 24 kg bag of sand. |\ | \ | \ { } | { == } | { } 15 g...

Hey, I am a bit confused about this... sorry if I am being stupid, I am only 16... I was thinking about hydrogen and the fact that it is less dense than air, and water and the fact that it is denser than air... Could the gpe gained by hydrogen, and the gpe converted into kinetic energy by...

I got this question on a study sheet however, I am not sure if I understand, I thought that there was no such thing as a lost of energy because it can not be destroyed. However it can convert into a different type of enery. Please help me get a clue.:rolleyes:

Homework Statement A bob is hung by a light string and and is pushed sideways. A peg of wood is placed vertically below the point of suspension of the string to hinder the motion of string as shown in the figure below: (please refer to the attachment) The bob is released. Which of the...

To All: I would like to invite both members and visitors of the PhysicsForums.com Engineering (Mechanical and Aerospace Engineering) Forum to start a discussion on Energy Conversion Systems -- ask questions of interest, share knowledge and experience related to Energy Conversion Systems...

How can you convert Mechanical energy into Considerable Heat Energy directly? The mecahnical energy has to be minimum. And the heat energy produced must be of great magnitude. Help!

Hi, Is it possible to convert heat energy into electrical energy. (Excluding boiler engines, ect...) Following along the lines of capacitance and capitors... Thanks. Derek Mohammed

An equation for energy conversion I wanted an equation to find the energy being used for time travel instead of space travel. Tell me if this works. N=(MC^2)[(C-S)/C] N representing energy converted to travel through time instead of space S representing speed M...

Is there any fairly simple way of converting energy in the form of heat to energy in the form of electricity or kinetic?

Maxwell’s Demon An Energy Conversion Experiment in Contradiction to the Second Law We have performed successfully an experiment of energy conversion of a totally new type. Please see the attachment figures. The experiment relates to a special electronic tube, which has two similar and...