Advertisements
Advertisements
प्रश्न
Explain the different ways through which the internal energy of the system can be changed.
Advertisements
उत्तर
- The internal energy of a system can be changed by changing the temperature of the system:
a. If the system is placed in an environment that is at a temperature lower than the system, i.e., TS > TE, the energy is transferred from the system to the environment causing a decrease in the internal energy of the system.
b. If the system is placed in an environment that is at a temperature higher than the system, i.e., TE > TS, the energy is transferred from the environment to the system causing the increase in the internal energy of the system. - The internal energy of a system can be changed by doing some work:
a. When some work is done on the system by the environment, the system gains energy, and its temperature increases causing an increase in internal energy.
b. When some work is done by the system on the environment, the system loses the energy, and its temperature decreases causing a decrease in internal energy.
APPEARS IN
संबंधित प्रश्न
Explain why Two bodies at different temperatures T1 and T2, if brought in thermal contact, do not necessarily settle to the mean temperature (T1 + T2)/2.
In changing the state of a gas adiabatically from an equilibrium state A to another equilibrium state B, an amount of work equal to 22.3 J is done on the system. If the gas is taken from state A to B via a process in which the net heat absorbed by the system is 9.35 cal, how much is the net work done by the system in the latter case? (Take 1 cal = 4.19 J)
Should the internal energy of a system necessarily increase if heat is added to it?
A cylinder containing a gas is lifted from the first floor to the second floor. What is the amount of work done on the gas? What is the amount of work done by the gas? Is the internal energy of the gas increased? Is the temperature of the gas increased?
Can work be done by a system without changing its volume?
An ideal gas is pumped into a rigid container having diathermic walls so that the temperature remains constant. In a certain time interval, the pressure in the container is doubled. Is the internal energy of the contents of the container also doubled in the interval ?
Consider the following two statements.
(A) If heat is added to a system, its temperature must increase.
(B) If positive work is done by a system in a thermodynamic process, its volume must increase.
Consider two processes on a system as shown in figure.
The volumes in the initial states are the same in the two processes and the volumes in the final states are also the same. Let ∆W1 and ∆W2 be the work done by the system in the processes A and B respectively.
A gas is contained in a metallic cylinder fitted with a piston. The piston is suddenly moved in to compress the gas and is maintained at this position. As time passes the pressure of the gas in the cylinder ______________ .
A substance is taken through the process abc as shown in figure. If the internal energy of the substance increases by 5000 J and a heat of 2625 cal is given to the system, calculate the value of J.
A gas is initially at a pressure of 100 kPa and its volume is 2.0 m3. Its pressure is kept constant and the volume is changed from 2.0 m3 to 2.5 m3. Its Volume is now kept constant and the pressure is increased from 100 kPa to 200 kPa. The gas is brought back to its initial state, the pressure varying linearly with its volume. (a) Whether the heat is supplied to or extracted from the gas in the complete cycle? (b) How much heat was supplied or extracted?
A mixture of fuel and oxygen is burned in a constant-volume chamber surrounded by a water bath. It was noticed that the temperature of water is increased during the process. Treating the mixture of fuel and oxygen as the system,
- Has heat been transferred?
- Has work been done?
- What is the sign of ∆U?
Define heat.
What is the internal energy of the system, when the amount of heat Q is added to the system and the system does not do any work during the process?
A system releases 100 kJ of heat while 80 kJ of work is done on the system. Calculate the change in internal energy.
Explain given cases related to energy transfer between the system and surrounding –
- energy transferred (Q) > 0
- energy transferred (Q) < 0
- energy transferred (Q) = 0
One gram of water (1 cm3) becomes 1671 cm3 of steam at a pressure of 1 atm. The latent heat of vaporization at this pressure is 2256 J/g. Calculate the external work and the increase in internal energy.
A cylinder containing one gram molecule of the gas was compressed adiabatically until its temperature rose from 27°C to 97°C. Calculate the work done and heat produced in the gas (𝛾 = 1.5).
An ideal gas is compressed at a constant temperature. Its internal energy will ____________.
Which of the following represents isothermal process?
Two cylinders A and B of equal capacity are connected to each other via a stopcock. A contains a gas at standard temperature and pressure. B is completely evacuated. The entire system is thermally insulated. The stopcock is suddenly opened. Answer the following:
What is the final pressure of the gas in A and B?
A person of mass 60 kg wants to lose 5kg by going up and down a 10 m high stairs. Assume he burns twice as much fat while going up than coming down. If 1 kg of fat is burnt on expending 7000 kilo calories, how many times must he go up and down to reduce his weight by 5 kg?
A cyclic process ABCA is shown in the V-T diagram. A process on the P-V diagram is ______.
A system releases 125 kJ of heat while 104 kJ work is done on the system. Calculate the change in internal energy.
Explain the change in internal energy of a thermodynamic system (the gas) by heating it.
