371312
An engineer claims to have made an engine delivering \(10\;kW\) power with fuel consumption of \(1\;g/s\). The calorific value of the fuel is \(2\,k\,cal/g\). The claim of the engineer
1 Invalid
2 Valid
3 Depends on engine design
4 Depends of the load
Explanation:
Input energy \( = \frac{{1g}}{s} \times \frac{{2k\,cal}}{g} = 2k\,cal/s\). Output \( = 10\;kW = 10KJ/S = \frac{{10}}{{4.2}}k\,cal/s\). \(\Rightarrow \eta=\dfrac{\text { output energy }}{\text { input energy }}=\dfrac{10}{4.2 \times 2}>1\)
PHXI12:THERMODYNAMICS
371313
An ideal heat engine working between temperature \(T_{1}\) and \(T_{2}\) has an efficinecy \(\eta\), the new efficiency if both the source and sink temperature are doubled, will be
1 \(\eta\)
2 \(\dfrac{\eta}{2}\)
3 \(3 \eta\)
4 \(2 \eta\)
Explanation:
In first case \(\eta_{1}=\dfrac{T_{1}-T_{2}}{T_{1}}\) In second case \(\eta_{2}=\dfrac{2 T_{1}-2 T_{2}}{2 T_{1}}=\dfrac{T_{1}-T_{2}}{T_{1}}=\eta\)
PHXI12:THERMODYNAMICS
371314
A steam engine delivers \(5.4 \times {10^8}\;J\) of work per minute and takes \(3.6 \times {10^9}\;J\) of heat per minute from the boiler. What is the efficiency of the engine?
1 \(25\,\% \)
2 \(15\,\% \)
3 \(30\,\% \)
4 \(35\,\% \)
Explanation:
Here, \(Q_{1}=\) Heat absorbed per minute \(Q_{2}=\) Heat rejected per minute We know that \(\eta \,\% = \frac{W}{{{Q_1}}} \times 100\) \(\eta \% = \frac{{5.4 \times {{10}^8}J}}{{3.6 \times {{10}^9}J}} \times 100 = \frac{3}{{20}} \times 100 = 15\,\% \)
371312
An engineer claims to have made an engine delivering \(10\;kW\) power with fuel consumption of \(1\;g/s\). The calorific value of the fuel is \(2\,k\,cal/g\). The claim of the engineer
1 Invalid
2 Valid
3 Depends on engine design
4 Depends of the load
Explanation:
Input energy \( = \frac{{1g}}{s} \times \frac{{2k\,cal}}{g} = 2k\,cal/s\). Output \( = 10\;kW = 10KJ/S = \frac{{10}}{{4.2}}k\,cal/s\). \(\Rightarrow \eta=\dfrac{\text { output energy }}{\text { input energy }}=\dfrac{10}{4.2 \times 2}>1\)
PHXI12:THERMODYNAMICS
371313
An ideal heat engine working between temperature \(T_{1}\) and \(T_{2}\) has an efficinecy \(\eta\), the new efficiency if both the source and sink temperature are doubled, will be
1 \(\eta\)
2 \(\dfrac{\eta}{2}\)
3 \(3 \eta\)
4 \(2 \eta\)
Explanation:
In first case \(\eta_{1}=\dfrac{T_{1}-T_{2}}{T_{1}}\) In second case \(\eta_{2}=\dfrac{2 T_{1}-2 T_{2}}{2 T_{1}}=\dfrac{T_{1}-T_{2}}{T_{1}}=\eta\)
PHXI12:THERMODYNAMICS
371314
A steam engine delivers \(5.4 \times {10^8}\;J\) of work per minute and takes \(3.6 \times {10^9}\;J\) of heat per minute from the boiler. What is the efficiency of the engine?
1 \(25\,\% \)
2 \(15\,\% \)
3 \(30\,\% \)
4 \(35\,\% \)
Explanation:
Here, \(Q_{1}=\) Heat absorbed per minute \(Q_{2}=\) Heat rejected per minute We know that \(\eta \,\% = \frac{W}{{{Q_1}}} \times 100\) \(\eta \% = \frac{{5.4 \times {{10}^8}J}}{{3.6 \times {{10}^9}J}} \times 100 = \frac{3}{{20}} \times 100 = 15\,\% \)
371312
An engineer claims to have made an engine delivering \(10\;kW\) power with fuel consumption of \(1\;g/s\). The calorific value of the fuel is \(2\,k\,cal/g\). The claim of the engineer
1 Invalid
2 Valid
3 Depends on engine design
4 Depends of the load
Explanation:
Input energy \( = \frac{{1g}}{s} \times \frac{{2k\,cal}}{g} = 2k\,cal/s\). Output \( = 10\;kW = 10KJ/S = \frac{{10}}{{4.2}}k\,cal/s\). \(\Rightarrow \eta=\dfrac{\text { output energy }}{\text { input energy }}=\dfrac{10}{4.2 \times 2}>1\)
PHXI12:THERMODYNAMICS
371313
An ideal heat engine working between temperature \(T_{1}\) and \(T_{2}\) has an efficinecy \(\eta\), the new efficiency if both the source and sink temperature are doubled, will be
1 \(\eta\)
2 \(\dfrac{\eta}{2}\)
3 \(3 \eta\)
4 \(2 \eta\)
Explanation:
In first case \(\eta_{1}=\dfrac{T_{1}-T_{2}}{T_{1}}\) In second case \(\eta_{2}=\dfrac{2 T_{1}-2 T_{2}}{2 T_{1}}=\dfrac{T_{1}-T_{2}}{T_{1}}=\eta\)
PHXI12:THERMODYNAMICS
371314
A steam engine delivers \(5.4 \times {10^8}\;J\) of work per minute and takes \(3.6 \times {10^9}\;J\) of heat per minute from the boiler. What is the efficiency of the engine?
1 \(25\,\% \)
2 \(15\,\% \)
3 \(30\,\% \)
4 \(35\,\% \)
Explanation:
Here, \(Q_{1}=\) Heat absorbed per minute \(Q_{2}=\) Heat rejected per minute We know that \(\eta \,\% = \frac{W}{{{Q_1}}} \times 100\) \(\eta \% = \frac{{5.4 \times {{10}^8}J}}{{3.6 \times {{10}^9}J}} \times 100 = \frac{3}{{20}} \times 100 = 15\,\% \)
371312
An engineer claims to have made an engine delivering \(10\;kW\) power with fuel consumption of \(1\;g/s\). The calorific value of the fuel is \(2\,k\,cal/g\). The claim of the engineer
1 Invalid
2 Valid
3 Depends on engine design
4 Depends of the load
Explanation:
Input energy \( = \frac{{1g}}{s} \times \frac{{2k\,cal}}{g} = 2k\,cal/s\). Output \( = 10\;kW = 10KJ/S = \frac{{10}}{{4.2}}k\,cal/s\). \(\Rightarrow \eta=\dfrac{\text { output energy }}{\text { input energy }}=\dfrac{10}{4.2 \times 2}>1\)
PHXI12:THERMODYNAMICS
371313
An ideal heat engine working between temperature \(T_{1}\) and \(T_{2}\) has an efficinecy \(\eta\), the new efficiency if both the source and sink temperature are doubled, will be
1 \(\eta\)
2 \(\dfrac{\eta}{2}\)
3 \(3 \eta\)
4 \(2 \eta\)
Explanation:
In first case \(\eta_{1}=\dfrac{T_{1}-T_{2}}{T_{1}}\) In second case \(\eta_{2}=\dfrac{2 T_{1}-2 T_{2}}{2 T_{1}}=\dfrac{T_{1}-T_{2}}{T_{1}}=\eta\)
PHXI12:THERMODYNAMICS
371314
A steam engine delivers \(5.4 \times {10^8}\;J\) of work per minute and takes \(3.6 \times {10^9}\;J\) of heat per minute from the boiler. What is the efficiency of the engine?
1 \(25\,\% \)
2 \(15\,\% \)
3 \(30\,\% \)
4 \(35\,\% \)
Explanation:
Here, \(Q_{1}=\) Heat absorbed per minute \(Q_{2}=\) Heat rejected per minute We know that \(\eta \,\% = \frac{W}{{{Q_1}}} \times 100\) \(\eta \% = \frac{{5.4 \times {{10}^8}J}}{{3.6 \times {{10}^9}J}} \times 100 = \frac{3}{{20}} \times 100 = 15\,\% \)
