Recent questions in Thermodynamics

The first law of thermodynamics following from

asked Mar 12, 2014 by yamini.v

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A heat engine operates between a cold reservoir at temperature $\;T_{2}=600 K\;$ & a hot reservoir at temperature $\;T_{1}\;.$ It takes 1000 J of energy from hot reservoir & gives 200 J . What can be the minimum temperature of the hot reservoir

asked Mar 12, 2014 by yamini.v

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A heat engine operates between a cold reservoir at temperature $\;T_{1}=300 K\;$ & a hot reservoir at temperature $\;T_{2}=600 K\;$ . It takes 500 J heat from hot reservoir and delivers x J of heat to cold reservoir in a cycle . Then x = ?

asked Mar 12, 2014 by yamini.v

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An engine intakes 10 g of steam per sec at $\;100^{0}C\;$ & cools it down to $\;50^{0}C\;$ . ( latent heat of vapourization of steam = 540 $\;calg^{-1}$ ) Heat rejected by engine per minute

asked Mar 12, 2014 by yamini.v

1 answer

An ideal gas is made to expand isothermally from $\;V_{1}\;$ to $\;V_{2}\;$ & is then compressed adiabatically to $\;V_{1}\;$ . Then the total work done is -

asked Mar 12, 2014 by yamini.v

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A ball is dropped from a height of $10\; m$ & it rises to a height of $5\; m$ . Assuming $\;50 \%\;$ of the energy goes into increasing temperature of ball , the temperature rise is (specific heat of ball's material = $\;1000 JK^{-1}$ )

asked Mar 12, 2014 by yamini.v

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If heat is supplied to a solid , its temperature -

asked Mar 12, 2014 by yamini.v

1 answer

Two balls of equal masses moving with $\;10 \;ms^{-1}\;$ towards each other collide after some time . Considering the collision to be inelastic & mass of each ball to be 1 kg , the thermal energy developed in the process is equal to what?

asked Mar 12, 2014 by yamini.v

1 answer

A vehicle (mass=1000 kg) , moving at a speed of $\;36 \;kmh^{-1}\;$ is stopped in 2 s . Assuming that $\;50 \%\;$ of the mechanical energy lost appears as thermal energy , the average rate of production of thermal energy in $\;cal s^{-1}\;$ is -

asked Mar 12, 2014 by yamini.v

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When a hot liquid sample is mixed with a cold one , the temperature of the mixture

asked Mar 12, 2014 by yamini.v

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A calorimeter (water equivalent = 25 g ) contains of 265 g of water at $\;30^{0}C\;$ . Steam is passed at $\;100^{0}C\;$ is passed which increases the temperature to $\;40^{0}C\;$ & the mass of the calorimeter and its contents by 2g . Given that the specific heat capacity of water is $\;1\;{calg^{-1}}^{0}C\;$ , the latent heat of vapourization of water is -

asked Mar 12, 2014 by yamini.v

1 answer

A bullet is fired into a box & penetrates it . The penetration process melts it . Assuming that $\;25 \%\;$ of its K.E . goes in heating & the initial and final temperature are $\;27^{0}C\;$ & $\;327^{0}C\;$ , the initial velocity is - (specific heat capacity = $\;100 Jkg^{-1}K^{-1}\;$ Latent heat of fusion = $\;2 \times 10^{4} Jkg^{-1}$ )

asked Mar 12, 2014 by yamini.v

1 answer

A ball is dropped from a height of 1000 Km .Due to heat from air friction & melts just before reaching the ground . The latent heat of fusion of ball's material is - (specific heat of material =100 $\;{J kg^{-1}}^{0}C$ Air tempeature= $\;25^{0}C\;$ , Melting point = $\;{J kg^{-1}}^{0}C\;$ )

asked Mar 12, 2014 by yamini.v

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The mechanical equivalent of heat -

asked Mar 12, 2014 by yamini.v

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As the temperature increases , the time period of the pendulum -

asked Mar 12, 2014 by yamini.v

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From a rectangular box , a circular portion is removed and the figure looks like - when the object is heated , the distance PQ -

asked Mar 12, 2014 by yamini.v

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A pendulum clock is made of iron rod $\;(\alpha_{iron}={10^{-5}}^{0}C^{-1})\;.$ At room temperature $\;(15^{0}C)\;,$ it works correctly . The error when the temperature rises to $\;24^{0}C\;$

asked Mar 12, 2014 by yamini.v

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A pendulum clock having copper rod keeps correct at $\;20^{0} C\;.$ It gains 15 seconds per day if cooled to $\;0^{0}C\;.$ Calculate the coefficient of linear expansion of copper :

asked Mar 12, 2014 by yamini.v

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Two plates each of area A, thicknesses L1 and L2 and thermal conductivities K1 and K2 are joined to form a single plate of thickness (L1 + L2). If the temperatures of the free surfaces are T1 and T2,Find the equivalent thermal conductivity:

asked Mar 10, 2014 by balaji.thirumalai

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Two plates each of area A, thicknesses L1 and L2 and thermal conductivities K1 and K2 are joined to form a single plate of thickness (L1 + L2). If the temperatures of the free surfaces are T1 and T2, Find the temperature of interface:

asked Mar 10, 2014 by balaji.thirumalai

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Two plates each of area A, thicknesses L1 and L2 and thermal conductivities K1 and K2 are joined to form a single plate of thickness (L1 + L2). If the temperatures of the free surfaces are T1 and T2, Find the rate of flow of heat:

asked Mar 10, 2014 by balaji.thirumalai

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