Advertisements
Advertisements
प्रश्न
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?
Advertisements
उत्तर
The first law of thermodynamics is one of the most useful equations when dealing with internal energy, and it states that the change in internal energy of a system equals the heat added to the system minus the work done by the system.
∆U = Q − W
APPEARS IN
संबंधित प्रश्न
Explain why Air pressure in a car tyre increases during driving.
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 force F is applied on a block of mass M. The block is displaced through a distance d in the direction of the force. What is the work done by the force on the block? Does the internal energy change because of this work?
The outer surface of a cylinder containing a gas is rubbed vigorously by a polishing machine. The cylinder and its gas become warm. Is the energy transferred to the gas heat or work?
Can work be done by a system without changing its volume?
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.
In a process on a system, the initial pressure and volume are equal to the final pressure and volume.
(a) The initial temperature must be equal to the final temperature.
(b) The initial internal energy must be equal to the final internal energy.
(c) The net heat given to the system in the process must be zero.
(d) The net work done by the system in the process must be zero.
Figure shows three paths through which a gas can be taken from the state A to the state B. Calculate the work done by the gas in each of the three paths.
A gas is taken through a cyclic process ABCA as shown in figure. If 2.4 cal of heat is given in the process, what is 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 system releases 130 kJ of heat while 109 kJ of work is done on the system. Calculate the change in internal energy.
Which of the following system freely allows the exchange of energy and matter with its environment?
When does a system lose energy to its surroundings and its internal energy decreases?
A system releases 100 kJ of heat while 80 kJ of work is done on the system. Calculate the change in internal energy.
Explain the different ways through which the internal energy of the system can be changed.
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.
derive the relation between the change in internal energy (∆U), work is done (W), and heat (Q).
Two samples A and B, of a gas at the same initial temperature and pressure are compressed from volume V to V/2; A isothermally and B adiabatically. The final pressure of A will be ______.
Which of the following represents isothermal process?
A gas is compressed at a constant pressure of 50 N/m2 from a volume of 10 m3 to a volume of 4 m3. Energy of 100 J is then added to the gas by heating. Its internal energy is ______.
The molar specific heat of He at constant volume is 12.47 J/mol.K. Two moles of He are heated at constant pressure. So the rise in temperature is 10 K. Find the increase in internal energy of the gas.
A steam engine delivers 4.8 x 108 Jof work per minute and services 1.2 x 109 J of heat per minute from its boiler. What is the percentage efficiency of the engine?
