AIEEE 2012 | Heat and Thermodynamics Question 403 | Physics

A Carnot engine, whose efficiency is $$40\% $$, takes in heat from a source maintained at a temperature of $$500$$ $$K.$$ It is desired to have an engine of efficiency $$60\% .$$ Then, the intake temperature for the same exhaust (sink) temperature must be :

efficiency of Carnot engine cannot be made larger than $$50\% $$

$$1200$$ $$K$$

$$750$$ $$K$$

$$600$$ $$K$$

AIEEE 2011

MCQ (Single Correct Answer)

-1

Three perfect gases at absolute temperatures $${T_1},\,{T_2}$$ and $${T_3}$$ are mixed. The masses of molecules are $${m_1},{m_2}$$ and $${m_3}$$ and the number of molecules are $${n_1},$$ $${n_2}$$ and $${n_3}$$ respectively. Assuming no loss of energy, the final temperature of the mixture is:

$${{{n_1}{T_1} + {n_2}{T_2} + {n_3}{T_3}} \over {{n_1} + {n_2} + {n_3}}}$$

$${{{n_1}T_1^2 + {n_2}T_2^2 + {n_3}T_3^2} \over {{n_1}{T_1} + {n_2}{T_2} + {n_3}{T_3}}}$$

$${{n_1^2T_1^2 + n_2^2T_2^2 + n_3^2T_3^2} \over {{n_1}{T_1} + {n_2}{T_2} + {n_3}{T_3}}}$$

$${{\left( {{T_1} + {T_2} + {T_3}} \right)} \over 3}$$

AIEEE 2011

MCQ (Single Correct Answer)

-1

$$100g$$ of water is heated from $${30^ \circ }C$$ to $${50^ \circ }C$$. Ignoring the slight expansion of the water, the change in its internal energy is (specific heat of water is $$4184$$ $$J/kg/K$$):

$$8.4$$ $$kJ$$

$$84$$ $$kJ$$

$$2.1$$ $$kJ$$

$$4.2$$ $$kJ$$

AIEEE 2011

MCQ (Single Correct Answer)

-1

A thermally insulated vessel contains an ideal gas of molecular mass $$M$$ and ratio of specific heats $$\gamma .$$ It is moving with speed $$v$$ and it's suddenly brought to rest. Assuming no heat is lost to the surroundings, Its temperature increases by:

$${{\left( {\gamma - 1} \right)} \over {2\gamma R}}M{v^2}K$$

$${{\gamma {M^2}v} \over {2R}}K$$

$${{\left( {\gamma - 1} \right)} \over {2R}}M{v^2}K$$

$${{\left( {\gamma - 1} \right)} \over {2\left( {\gamma + 1} \right)R}}M{v^2}K$$

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