Processing math: 39%




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16.

A carnot  engine  with efficiency η operates between two heat  reservoirs with temperatures T1 and T2  , where T1>T2 . If only T1 is changed by 0.4% , the  change in efficiency is η1 , whereas if only  T2  is changed by 0.2% , the efficiency is changed by η2 . The ratio  η1η2 is approximately


A) -2

B) -4

C) +3

D) +4



17.

A water tank kept on the ground has an orifice of 2 mm diameter on the vertical side. What is the minimum height of the water above the orifice for which the output flow of water is found to be turbulent? [ Assume  g=10 m/s2, ρwater= 103 kg/m3, viscosity =1 centi-poise]


A) 3 cm

B) 4 cm

C) 6 cm

D) 2 cm



18.

A body of mass 0.3 kg hangs by a spring with a force constant of 50N/m . The amplitude of oscillations is damped and reaches \frac{1}{e} of its original value in about 100 oscillations. If \omega and \omega' are the angular frequencies of undamped and damped oscillations respectively , then percentage of  \left(\frac{\omega-\omega'}{\omega}\right) is 


A) \left(\frac{1}{800 \pi}\right)

B) \left(\frac{\pi^{2}}{600 }\right)

C) \left(\frac{1}{800\pi^{2} }\right)

D) \left(\frac{\pi}{400 }\right)



19.

A rocket motor consumes 100 kg of fuel per second exhausting it with a speed of 5 km/s. The speed of the rocket when its mass is  reduced to  \frac{1}{20}^{th}  of its initial mass, is [Assume initial speed  to be zero and ignored gravitational and viscous forces]


A) 20 km/s

B) 40 in (2) km/s

C) 5 in (20) km/s

D) 10 in (10) km/s



20.

A particle A moves along the line, y=30m with a constant velocity, v parallel to the x-axis. At the momemt particle A passes the y-axis, particle  B starts from the origin  witrh zero  initial speed and a constant acceleration  .a=0.40 m/sec^{2} . The angle between a and y-axis is 60^{0}. If the particles A and B collide after sometimes , then the value of |v|  will be


A) 2 m/s

B) 3 m/s

C) 4 m/s

D) 5 m/s



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