Laws of Thermodynamics Physics - Laws of Thermodynamics

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

1. Calculate the work done by the gas.
2. If no heat is supplied or extracted from the gas, what is the change in the internal energy of the gas?

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

A gas is enclosed in a cylindrical vessel fitted with a frictionless piston. The gas is slowly heated for some time. During the process, 10J of heat is supplied and the piston is found to move out 10cm. Find the increase in the internal energy of the gas. The area of cross section of the cylinder = 4cm² and the atmospheric pressure = 100kPa.

An ideal gas is taken from an initial state i to a final state f in such a way that the ratio of the pressure to the absolute temperature remains constant. What will be the work done by the gas?

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?

Should the internal energy of a system necessarily increase if heat is added to it?

What should be the condition for the efficiency of a Carnot engine to be equal to 1?

When we heat an object, it expands. Is work done by the object in this process ? Is heat given to the object equal to the increase in its internal energy?

Calculate the change in internal energy of a gas kept in a rigid container when 100J of heat is supplied 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?

Should the internal energy of a system necessarily increase if its temperature is increased?

When we rub our hands they become warm. Have we supplied heat to the hands?

A closed bottle contains some liquid. The bottle is shaken vigorously for 5 minutes. It is found that the temperature of the liquid is increased. Is heat transferred to the liquid? Is work done on the liquid? Neglect expansion on heating.

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?

When a tyre bursts, the air coming out is cooler than the surrounding air. Explain.

An ideal gas goes from the state i to the state fas shown in figure. The work done by the gas during the process:

1. Is positive.
2. Is negative.
3. Is zero.
4. Cannot be obtained from this information.

The internal energy of an ideal gas decreases by the same amount as the work done by the system:

1. The process must be adiabatic.
2. The process must be isothermal.
3. The process must be isobaric.
4. The temperature must decrease.

In a process on a system, the initial pressure and volume are equal to the final pressure and volume.

1. The initial temperature must be equal to the final temperature.
2. The initial internal energy must be equal to the final internal energy.
3. The net heat given to the system in the process must be zero.
4. The net work done by the system in the process must be zero.

The first law of thermodynamics is a statement of:

1. Conservation of heat.
2. Conservation of work.
3. Conservation of momentum.
4. Conservation of energy.

A 100kg block is started with a speed of 2.0ms^-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.

1. Calculate the change in the internal energy of the block-belt system as the block comes to a stop on the belt.
2. Consider the situation from a frame of reference moving at 2.0ms^-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 2.0ms^-1 Calculate the increase in the kinetic energy of the block as it stops slipping past the belt.
3. Find the work done in this frame by the external force holding the belt.

A thermally insulated, closed copper vessel contains water at 15°C. When the vessel is shaken vigorously for 15 minutes, the temperature rises to l 7°C. The .mass of the vessel is 100g and that of the water is 200g. The specific heat capacities of copper and water are 420Jkg^-1 K^-1 and 4200Jkg^-1 K^-1 respectively. Neglect any thermal expansion.

1. How much heat is transferred to the liquid-vessel system?
2. How much work has been done on this system?
3. How much is the increase in internal energy of the system?

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

The internal energy of a gas is given by U = 1.5PV. It expands from 100cm³ to 200cm³ against a constant pressure of 1.0 x 10⁵Pa. Calculate the heat absorbed by the gas in the process.

50cal of heat should be supplied to take a system from the state A to the state B through the path ACB as shown in figure. Find the quantity of heat to be supplied to take it from A to B via ADB.