Physics internal energy heat problems, several junior high school physics questions, the relationshi

2,5 pairs.

1, 3, 4, 6 are not right.

1: In fact, the increase in internal energy here can be regarded as the object absorbing heat, but the object does not necessarily reach the specific heat capacity, so the temperature does not necessarily increase.

3: Heat is the amount of process, and it cannot be said to be there. This question seems to say that the object has heat4: the object absorbs heat, but does not necessarily achieve the specific heat capacity. Therefore, the temperature does not necessarily increase6: it may be that the outside world has done work on it, causing the temperature to rise.

2: The concept of internal energy is the sum of the kinetic and potential energy of molecules in an object. From the theory of molecular kinetics, it can be seen that the temperature increases, the more intense the motion of the molecules, so that the kinetic energy of the molecules increases. So the internal energy increases.

5: Seems to be about the same as 2.

235 to 1, if the internal energy of the crystal increases during the melting process, the temperature does not rise, and 4 the crystal absorbs heat during the melting process.

The temperature does not rise.

6. The increase in the internal energy of the object can also be done by the method of work.

Solution: The heat emitted by the radiator every day: Q = to the 6th power J x 24 = to the 8th power J

Hot water flowing through the radiator every day: m=q [c(t -t)]= to the 8th power [.]

A: Every day, 1800 kilograms of 50 degrees of hot water flow through the radiators.

1. Wrong, reason: the heat released is also related to the number of temperature reductions, if it is not cooled, it is not heated, or the heat released is less when it is cooled down.

2. Yes, when the temperature increases, the speed of molecular movement increases, and the kinetic energy of the molecule increases, so the internal energy increases.

3, yes, the internal energy is not only related to the temperature, and the state of matter is related, in the case of the same state of matter, the higher the temperature, the greater the kinetic energy of the molecule, the greater the internal energy, this just explains the 2 questions (in the 2 questions limit the iron block and the temperature) and the 3 questions obviously have a change in the state of matter, it can not be measured by temperature alone, we know that the solidification of water into ice is an exothermic process, and the heat released obviously comes from the internal energy to recognize the reduction of internal energy, which is correct.

4. False, internal energy is the energy of the microcosm inside the object, and the kinetic energy of the object is mechanical energy, which is the energy of the macrocosm, although the two forms of energy can be converted into each other under certain conditions, but there is no inevitable connection between the two, so it cannot be said that there must be kinetic energy if there is internal energy, or that there must be internal energy if there is kinetic energy.

The internal energy is present in all objects, but the kinetic energy of the object is not necessarily, if it is at rest then the kinetic energy is zero.

I hope my explanation can help you, and I wish you progress in your studies!

Exothermic requires not only a heat source but also a cold source, 1 wrong.

2 is right. The internal energy includes the kinetic energy of the molecule and the potential energy, the kinetic energy (temperature) of the molecule increases, the potential energy almost does not change, and the internal energy increases.

Water solidification is an exothermic reaction with reduced internal energy.

Internal energy has nothing to do with kinetic energy. An object must have internal energy, not necessarily kinetic energy.

Another person is wrong when he says that water solidification is due to the formation of hydrogen bonds, which reduces the potential energy and makes the intermolecular structure more stable.

The statement of 1 is not true, first of all, Q=cm(t2-t1) for c, the heat emitted is related to the properties of the substance itself, and the mass is large, which is true, and the temperature is high, which does not mean that the temperature difference is large, so this statement is not true.

2 The iron block heats up, the thermal motion between the molecules increases, and the internal energy increases.3 Ice and water are the same substance, and its freezing point 0 can be liquid or solid, but the volume increases, and the potential energy of the molecule increases, and the internal energy increases, so it is not right.

4 Objects with internal energy have potential energy between molecules and thermal motion of molecules But objects can be stationary The latter sentence is even more wrong.

1 False It is related to the temperature difference.

2 For an object (mass) is constant, the internal energy is only related to temperature.

3 pairs of simple thinking can be considered as conservation of energy.

4. The internal energy is related to temperature, not speed.

The work done by the engine on the aircraft should be equal to the amount of heat provided by the gasoline:

First of all, find the work done by the engine on the aircraft: w=p't

Because the power of the engine is 1200kw and the efficiency is 30%, the actual power provided by the engine to the aircraft p' = 1200kw 30% = 360kw =

The speed of the aircraft is 120km h, the distance covered is 2000km, and the flight time t=2000km 120kmh=(50 3)h=6 10 4s

w=p't=

Then ask: finally the heat that gasoline needs to provide:

set, should be prepared gasoline m kg.

The amount of heat provided by gasoline q=mq

Finally: the work done by the engine on the aircraft is equal to the heat provided by gasoline, which is: q=w i.e. mq=

m=m=

The flight duration of the aircraft is t s v 2000 120 50 3 hours 60000 seconds.

The minimum amount of gasoline required is m kilograms.

then p* t m*30%.

The desired mass of gasoline is m kilograms.

Flew 120km at a speed of 2000km, the required time t = s v=100 6 h

Therefore, the whole process of work is w=1200kw 100 6h=1200kw 60000s=72000000000j

The efficiency is 30, so the total work required to produce so much useful work is the total w = w Divide the total w by the heat of gasoline The value is the mass, and without a calculator, this step is not counted.

The flight time of the aircraft is 2000, 120=

The required work is 1200kw*30%*;

Suppose you need mkg gasoline, then there is m * to the seventh power j kg = the above formula, solve the equation to find m, pay attention to kwh and j to unify the next unit, you convert it yourself, the idea is very clear.

The total work it does = w = pt = 1200kw (2000km divided by 120km h) = 20000kwh

The efficiency is 30%, so the work of fuel combustion = 20000kWh divided by 30% times to the 6th power = to the 11th power.

Fuel required = (to the 11th power) divided by (to the seventh power j kg) = 120,000 23 is approximately equal to.

The mass of the nail is small, and the specific heat is small;

A has a large mass, a small specific heat, and a smaller product than B;

A has a small mass, a large specific heat, and a smaller product than B.

1. The mass is equal to that of the hot nail.

2 is equal to the heat of the mass of A.

3. The mass of the nail is smaller, smaller than the hot one.

4 mass nails are larger, smaller than hot nails.

5 is larger than the heat armor, and the mass is smaller.

1. The mass is the same, and the specific heat capacity of B is greater than that of A.

2. The mass of A is greater than that of B, and the specific heat capacity of B is greater than that of A.

3. The quality of A is smaller than that of B, and it is difficult to say that there may be no accurate data.

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.

Solution: 1).

Obtained by q cmt.

t＝q÷cm

2) (A: The temperature of this water rises to 65, and the solar energy that the water heater receives before receiving it is equivalent to the heat emitted by completely burning the kilogram of coal per acre.