Work

Q. What is the change in internal energy for an isothermal process?

Q. The specific heat of hydrogen gas at constant pressure is $C_P=3.4\times {10}^{3}cal/k{g}^{\circ }C$ and at constant volume is $C_r=2.4\times {10}^{3}cal/k{g}^{\circ }C$ If one kilogram hydrogen gas is heated from ${10}^{\circ }$ to ${20}^{\circ }$ at constant pressure, the external work done on the gas to maintain it at constant pressure is

1. 
2. 
3. 
4. 

Q. The P-V diagram of 2 gm of helium gas for a certain process A $\to$ B is shown in the figure. what is the heat given to the gas during the process A $\to$ B

1. 
2. 
3. 
4. 

Q.

The pressure of a gas changes linearly with volume from 10 kPa, 200 cc to 50 kPa. 50 cc.

(a) Calculate the work done by the gas.

(b) If no heat is supplied or extracted from the gas, what is the change in the internal energy of the gas ?

Q. The total work done on a Particle is equal to the change in its kinetic energy

1. Always
2. Only if the forces acting on it are conservative.
3. Only if gravitational force acts on it.
4. Only if Elastic Force acts on it.

Q. If the kinetic energy of a satellite orbiting around the earth is doubled, then

1. the satellite will escape into the space.
2. the satellite will fall down on the earth.
3. radius of its orbit will be doubled.
4. radius of its orbit will become half.

Q.

If the heat 110 J is added to a gaseous system and it acquires internal energy of 40 J, then the amount of internal work done is

1. 150 J
2. 40 J
3. 110 J
4. 70 J

Q. $540$ calories of heat convert $1\text{cc}$ of water at ${100}^{\circ }\text{C}$ to $1670\text{cc}$ steam at ${100}^{\circ }\text{C}$ at a pressure of $1\text{atm}$. Then the work done against the atmospheric pressure is nearly (Take atmospheric pressure, $P=1.01\times {10}^6{\text{dyne/cm}}^2$)

1. $40\text{cal}$
2. $30\text{cal}$
3. $10\text{cal}$
4. $16.7\text{cal}$

Q. 540 calories of heat convert 1 cubic centimeter of water at ${100}^{\circ }C$ into 1671 cubic centimeter of steam at ${100}^{\circ }C$ at a pressure of one atmosphere. Then the work done against the atmospheric pressure is nearly

1. 540 cal
2. 40 cal
3. Zero cal
4. 500 cal

Q. The equation of state for a gas is given by $PV=nRT+\alpha V$, where $n$ is the number of moles and $\alpha$ is a positive constant. The initial pressure and temperature of 1 mole of the gas contained in a cylinder are $P_0$ and $T_0$ respectively. The work done by the gas when its temperature doubles isobarically is

1. $W=\frac{P_{0}R{T}_0}{P_0-\alpha }$
2. $W=\frac{R{T}_0}{P_0-\alpha }$
3. $W=\frac{2P_{0}R{T}_0}{P_0-\alpha }$
4. $W=\frac{P_{0}R{T}_0}{2(P-\alpha )}$

Q. A gas expands with temperature according to the relation $V=k{T}^{2/3}$. What is the work done, when the temperature changes by ${30}^{\circ }\text{C}$?

1. $20R$
2. $30R$
3. $10R$
4. $40R$

Q. A block of mass 2 kg is free to move along the x-axis. It is at rest and from t = 0 onwards it is subjected to a time-dependent force F(t) in the x direction. The fore F(t) varies with t as shown in the figure. The kinetic energy of the block after 4.5 seconds is

(F)t

Q.

$1$-mole atom of diatomic gas at NTP will be $11.2\mathrm{L}$ liters.

Q. A vessel contains $14\text{g}$ of nitrogen gas at a temperature of ${27}^{\circ }C$. The amount of heat to be transferred to the gas to double the r.m.s speed of its molecules will be:
Take $R=8.32{\text{J mol}}^{–1}{\text{K}}^{–1}$.

1. $5616\text{J}$
2. $9360\text{J}$
3. $2229\text{J}$
4. $13104\text{J}$

Q. Internal energy of a non - ideal gas depends upon

1. Pressure
2. Volume
3. All of these
4. Temperature

Q. The adiabatic Bulk modulus of a perfect gas at pressure $P$ is given by

1. $P$
2. $2P$
3. $P/2$
4. $\gamma P$

Q.

Which of the following is zero for an isochoric process?

1. Volume

2. Temperature

3. Pressure

4. None of the above

Q.

A gas expands $0.25m^3$ at constant pressure ${10}^{3}N/m^2$, the work done is

1. 2.5 ergs

2. 250 J

3. 250 W

4. 250 N

Q. A square coil of side $l$ carries a current $I$. It is kept on a smooth horizontal surface. A uniform magnetic field exists in the region, directed in the plane of the coil as shown in the figure. what should be the minimum value of $B$, so that the coil will start tipping over ? Mass of the coil is $M$ and it has $N$ number of turns.

1. $\frac{mg}{2NIl}$
2. $\frac{Mg}{NIl}$
3. $\frac{Mg}{NI{l}^2}$
4. $\frac{Mg}{2NI{l}^2}$

Q. An ideal gas is made to go through a cyclic thermodynamic process in four steps. The amount of heat involved are $Q_1=600{\text{J, Q}}_2=-400{\text{J, Q}}_3=-300{\text{J and Q}}_4=200\text{J}$ respectively. The corresponding work involved are $W_1=300{\text{J, W}}_2=-200{\text{J, W}}_3=-150{\text{J and W}}_4$.
What is value of $W_4$?

1. $-50\text{J}$
2. $100\text{J}$
3. $150\text{J}$
4. $50\text{J}$

Q. A gas has molar heat capacity $C=37.35\text{J}{\text{mol}}^{-1}{\text{K}}^{-1}$ in the process $PT=\text{constant}$. Find the number of degrees of freedom of molecules in the gas.

1. $4$
2. $5$
3. $2$
4. $3$

Q.

The average translational energy and the rms speed of molecules of a sample of oxygen gas at $300k$ are

$6.21\times {10}^{-21}J$ and $484m{s}^{-1}$ respectively. The corresponding values at $600K$ are nearly (assuming ideal

gas behavior)

1. 

2. 

3. 

4. 

Q. A perfect gas contained in a cylinder is kept in vacuum. If the cylinder suddenly bursts, then the temperature of the gas

1. decreases
2. becomes zero
3. remains constant
4. increases

Q.

A man rowing a boat upstream is at rest with respect to the shore, is he doing work?

Q.

In an isothermal expansion

1. Internal energy of the gas decreases

2. Internal energy of the gas increases

3. Average kinetic energy of gas molecule decreases

4. Internal energy remains unchanged

Q. Figure shows the force versus displacement graph of the particle. Find out the work done by the force to displace the particle from $x=0$ to $x=20\text{m}$.

1. $150\text{Nm}$
2. $250\text{Nm}$
3. $200\text{Nm}$
4. $100\text{Nm}$

Q. Two Carnot heat engines are put in series such that heat rejected by one engine is used in the second engine as heat input. If efficiency of first engine is $30\text{\%}$, and overall combination has efficiency of $65\text{\%}$, then the efficiency of second engine is

1. $20\text{\%}$
2. $35\text{\%}$
3. $40\text{\%}$
4. $50\text{\%}$

Q.

An accelerated electron has energy of $9.6x{10}^{-18}J$. Express the energy in electron volts (eV)

Q.

Work done by a system under isothermal change from a volume $V_1$ to $V_2$ for a gas which obeys Vander Waals equation $(V-\beta n)(P+\frac{\alpha n^2}{V})=nRT$

1. 

2. 

3. 

4. 

Q. A coolie is walking on a horizontal platform with a load placed on his head. The mass of load is $5\text{kg}$. If the coolie travels a distance of $10\text{m}$, the workdone by him on the load is :

1. $500\text{J}$
2. $500\text{J}$
3. zero
4. $1000\text{J}$