To ensure turbulent conditions and minimum mixing time during agitation with a turbine impeller, the Reynolds number must be at least 10⁴. A stirred laboratory-scale fermenter with a turbine impeller 5 cm in diameter is operated at 800 rpm. If the density of broth being stirred is close to that of water. The mixing system is scaled up so the tank and impeller are 15 times the diameter of the laboratory equipment. The stirrer in the large vessel is operated so that the stirrer tip speed (tip speed = π N i D i) is the same as in the laboratory apparatus. How does scale-up affect the maximum viscosity. 

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#Question id: 7499

#Part-A Aptitude & General Biotechnology

Two trains, one from A to B and the other from B to A, start simultaneously. After theymeet, the trains reach their destinations after 4 h and 9 h respectively. The ration of their speeds is

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#Question id: 7500

#Part-A Aptitude & General Biotechnology

A man is standing on a railway bridge which is 180 m long. He finds that a train crosses the bridge in 20 seconds but himself in 8 seconds. Find the length of the train and its speed.

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#Question id: 7501

#Part-A Aptitude & General Biotechnology

A train 150 m long is running with a speed of 68 kmph. In what time will it pass a man who Is running at 8 kmph in the same direction in which the train is going?

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#Question id: 7502

#Part-A Aptitude & General Biotechnology

A train 220 m long is running with a speed of 59 kmph. In what time will it pass a man who is running at 7 kmph in the direction opposite to that in which the train is going?

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#Question id: 7503

#Part-A Aptitude & General Biotechnology

Two trains 137 metres and 163 metres in length are running towards each other on parallel lines,one at the rate of 42 kmph and another at 48 kmph. In what time will they be clear of each other from the moment they meet?

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#Question id: 7504

#Part-A Aptitude & General Biotechnology

Two train 100 metres and 120 metres long are running in the same direction with speed of 72 km/hr and 54 km/hr. In how much time will the first train cross the second?