हिंदी

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? - Physics

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?

एक पंक्ति में उत्तर
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

shaalaa.com
Heat, Internal Energy and Work
  क्या इस प्रश्न या उत्तर में कोई त्रुटि है?
अध्याय 4: Thermodynamics - Very Short Answer

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.


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?


The final volume of a system is equal to the initial volume in a certain process. Is the work done by the system necessarily zero? Is it necessarily nonzero?


Can work be done by a system without changing its volume?


The pressure p and volume V of an ideal gas both increase in a process.

(a) Such a process is not possible.

(b) The work done by the system is positive.

(c) The temperature of the system must increase.

(d) Heat supplied to the gas is equal to the change in internal energy.


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.


A 100 kg lock is started with a speed of 2.0 m s−1 on a long, rough belt kept fixed in a horizontal position. The coefficient of kinetic friction between the block and the belt is 0.20. (a) Calculate the change in the internal energy of the block-belt system as the block comes to a stop on the belt. (b) Consider the situation from a frame of reference moving at 2.0 m s−1 along the initial velocity of the block. As seen from this frame, the block is gently put on a moving belt and in due time the block starts moving with the belt at 2.0 m s−1. calculate the increase in the kinetic energy of the block as it stops slipping  past the belt. (c) Find the work done in this frame by the external force holding the belt.


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 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 taken along the path AB as shown in figure. If 70 cal of heat is extracted from the gas in the process, calculate the change in the internal energy of the system.


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,

  1. Has heat been transferred?
  2. Has work been done?
  3. What is the sign of ∆U?

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? 


What is the energy associated with the random, disordered motion of the molecules of a system called as?


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. 


A thermodynamic system goes from states (i) P, V to 2P, V  (ii) P, V to P, 2V. The work done in the two cases is ______.


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 ______.


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 change in the temperature of the gas?


In insulated systems, the amount of external work done by the gas is proportional to: 


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?


n mole of a perfect gas undergoes a cyclic process ABCA (see figure) consisting of the following processes:

A `→` B: Isothermal expansion at temperature T so that the volume is doubled from V1 to V2 = 2V1 and pressure changes from P1 to P2.

B `→` C: Isobaric compression at pressure P2 to initial volume V1.

C `→` A: Isochoric change leading to change of pressure from P2 to P1.

Total workdone in the complete cycle ABCA is ______.


An expansion process on a diatomic ideal gas (Cv = 5/2 R), has a linear path between the initial and final coordinates on a pV diagram. The coordinates of the initial state are: the pressure is 300 kPa, the volume is 0.08 m3 and the temperature is 390 K. The final pressure is 90 kPa and the final temperature s 320 K. The change in the internal energy of the gas, in SI units, is closest to:


The internal energy of one mole of argon is ______.


A system releases 125 kJ of heat while 104 kJ work is done on the system. Calculate the change in internal energy.


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×