Energy Physics Questions, Physics Questions about energy

1.The refrigeration power is 70W, and the total of 10min is 70*600=42000J=42KJ

2.Energy is conserved, also 42kj

Question 1 Same as above, Question 2:

Two parts. Part 1: Heat Exhaust from the Refrigerator.

Part 2: Since the refrigerator has a refrigeration efficiency of 70%, there is a 30% loss, which is also used to change the heat outside the refrigerator

That is: 100W*30%*60S*10min=18kJ;

You can also do this for this question:

The total power of the refrigerator is 100W, and all of these 100W are, whether it is the loss part or the work part, it is finally turned into heat energy, so there is:

100*10*60=60kj

a) The most power generation during the day is the electrical energy converted by the gravitational potential energy of all water, and the potential energy of water ep=rho*v*g*h=1000*8850000*10*600=

Since the efficiency is, the actual power generation is.

1 kWh = , maximum power generation = kWh during the day.

At night, it is a reverse process, the maximum work is done, the efficiency is the degree.

b) As long as there is one reason, it can be explained that there is friction in the mechanical parts of the pumping machine and the generator, so there is no need to provide a part of the energy to overcome the friction and do the work of power generation or pumping, resulting in the efficiency of both cannot reach 100%. Of course, there are many factors that actually cause the mechanical efficiency to not reach 100%, for example, when the power generation is delayed, the blade design of the generator is unreasonable, which will also lead to the loss of useful work, and the pipeline has head loss along the way when pumping, if the layout is unreasonable, there is a sharp turn or something, and there is a large local head loss, which will lead to the reduction of mechanical efficiency.

There are probably two explanations, and I personally think they are.

The elastic potential energy of the spring on the macroscopic level is reflected in the microscopic distortion of the chemical bonds between and within the molecules, and the energy stored in the distortion of a huge number of chemical bonds is reflected in the overall potential energy on the macroscopic level. At the micro level, this elastic potential energy is dispersed within each chemical bond – that is, each chemical bond is a small spring.

Then when the spring is immersed in acid and corroded (let's assume an ideal situation, i.e., the whole spring is corroded instantaneously at the same time), the elastic potential energy of all twisted chemical bonds will be released - we can even understand that each corroded ion will "bounce" out faster than if the spring is not compressed, that is, the energy in the system is greater.

On a macro scale, this is the case – all elastic potential energy eventually becomes the internal energy of an acidic solution (containing spring molecules or ions). Therefore, the temperature of the total system is higher than that of the acid soaked in the compressed spring than that of the acid soaked in the uncompressed spring, of course, this difference is probably not measured by the thermometer.

It's okay not to be a stretch party?

There is also an explanation for yourself to guess.

By the law of energy conversion and conservation, the elastic potential energy generated by the compression of the spring is converted into the energy in the system with the dissolution of the spring, which increases the temperature of the solution.

The potential energy of the spring is w=1 2*k*x 2, which is very small compared with the reaction heat of hydrochloric acid, and the potential energy can be ignored, while the specific heat capacity of dilute hydrochloric acid is 4More kilojoules per kilogram per degree, this is also far from the potential energy of the spring, so it is too weak to detect the potential energy of the spring by heating.

The essence of a chemical reaction is that the old bond breaks and a new bond is formed.

The so-called bond energy is just a statistical result of a large number of old bond breakage and new bond formation, and is not static.

You can't say that keys don't change.

According to my current opinion, the elastic potential energy of the spring is also converted into thermal energy.

Black smoke indicates inadequate combustion. A high temperature around the boiler indicates that the boiler releases a large amount of energy to the outside world in the form of thermal radiation. Improvement measures: Introduce enough air to fully burn the fuel and add thermal insulation.

The condensing method is adopted, and the condensing device is set around the flue gas pipe, and the waste heat is reasonably utilized.

The compressed spring reserves this energy.

Elastic potential energy is generated by the elastic interaction between the parts when the object undergoes elastic deformation. Its size varies with the relative position between the parts. Elastic potential energy is premised on the presence of elastic force.

Since there is no spring, there will be no elastic potential energy.

In addition, the spring will not compress itself, so there must be something fixed and put hydrochloric acid into the spring together, such a system cannot be deformed, equivalent to a plastic object, regardless of the elastic potential energy.

Seek adoption

Analysis: 1. Let the velocity of the moment before the collision be v1 and v2 respectively, then there is.

a= g, (v01) 2-(v1) 2 ] 2 g + v02) 2-(v2) 2 ] 2 g = d, i.e. 100-(v1) 2 + 4-(v2) 2=3400 ,v01)-(v1) ]g + v02)-(v2) ]g = t, i.e. 10-v1+2-v2=200, the above equation can be solved v1=,v2=,2, the collision process.

From the conservation of momentum, m1v1-m2v2=(m1+m2)v, the mechanical energy lost after the collision to the stop.

e=1/2*(m1+m2)v^2

This is the solution to this problem, I didn't help you calculate the result, can you do it yourself?

There is a correct solution to this question, but the process of correct solution is as troublesome as the last big question in the final exam, mainly because it is not easy to type. The reason for d, the exact expression is not given, because it is made up of a bunch of letters. Here's an inaccurate answer to you:

mgt+ft1-ft2 is the change in momentum of the whole process, t1 is the upward time, and t2 is the downward time, because when the object moves upward, the friction force is downward, which is consistent with gravity, and when the object moves downward, the friction force is upward, which is opposite to gravity.

The direction of gravity is all the way down during the whole process, and the impulse of gravity is mgt

In the ascending process, the direction of gravity and air resistance are both downward, while the direction of the drag force in the descending process is opposite to the direction of gravity, so the acceleration of the ascending process is greater than the acceleration of the descending process, so the ascending time is shorter than the descending time, and the air resistance of the whole process remains the same.

When the object moves upward, the friction is downward, and when the object moves downward, the friction is upward.

This problem cannot be conserved by mechanical energy, because there is a slight plastic deformation in the process of pulling the prime element at any moment, and the mechanical energy is partially converted into internal energy, similar to the model of the train carriage being pulled, there is an internal force to do the work, and the kinetic energy theorem must consider this, which is not easy to start. Apply the momentum theorem.

ygdt=dmv=mdv+vdm= (ydv+vdy) are eliminated first, then multiplied by dy dt, and notice that v=dy dt gives the differential equation:

gydy=yvdv+v 2dy combined with the initial condition y=0 v=0, and this equation is solved.

1/2 m v^2 = 1/2 k a^2m a = k a, a = m a / km v^2 = k m^2 a^2 / k^2k = m a^2 / v^2

Substituting the data.

k = 1400*(5* / (90*1000/3600)^2 = n/m

In addition, the formula v1 2-v2 2=2ax cannot be used, because the premise of this formula is a uniform variable speed, i.e. a = constof movement.

(1) Chemical energy: in fuel;

2) Kinetic energy: cars on the highway;

3) Gravitational potential energy: stones on the top of a mountain;

4) Elastic potential energy: stretch the spring;

5) Light energy: sun;

6) Internal energy: All objects have internal energy;

7) Nuclear energy: nuclear reactors in nuclear power plants;

8) Electricity: battery;

9) Magnetic energy: magnet;

10) Hydro: sea;

11) Wind energy: natural wind;

12) Geothermal energy: Earth;

13) Radiant energy: radioactive atoms. Such as "radium".

Chemical energy: There is in the fart.

Kinetic energy: An object in motion.

Gravitational potential energy: An object that is far from the ground.

Thermal energy, wind energy, hydro energy, electromagnetic energy.

Internal energy, a property that any object has, is produced by molecular motion; Chemical; electrical energy, through electromagnetic induction or chemical reactions; nuclear energy, mass loss through nuclear fusion or nuclear fission; Solar energy, needless to say, seems to be a large-scale nuclear reaction of the entire planet; Wind energy; Water; Terrestrial heat;