MAH-MHT CET (PCM/PCB) entrance exam Question Bank Solutions

The speed at which the flow of water in a long cylindrical pipe of diameter 6 cm becomes turbulent is ______

(The viscosity of water = 1 x 10^-3 Pa.s and for the onset of turbulent flow in a long cylindrical pipe, Reynolds number = 3000) 

Reynold's number is less for ______. 

The radiation energy density per unit wavelength at a temperature T has a maximum at a wavelength `lambda_0.` At temperature 4T, it will have a maximum at a wavelength ____________.

A blackbody emits radiations of maximum intensity at a wavelength of 6000 A, when the temperature of the body is 1227 °C. If the temperature of the body is increased by 2227 °C, the maximum intensity of emitted radiation would be observed at ______.

A blackbody is at a temperature of 5760 K. The energy of radiation emitted by the body at wavelength 250 nm is U₁, at wavelength 500 nm is U₂ and that at 1000 nm is U₃. Wien's constant, b = 2.88 x 10⁶ nmK. Which of the following is correct?

At a fixed wavelength, the `"E"_lambda` - T graph for an ideal blackbody is ____________.

Water is flowing through a tube of diameter 1 cm at 6 cm/s. Taking `eta` = 10^-2 poise the flow of liquid and Reynold's number are ____________.

The maximum average velocity of water in a tube of diameter 4 cm so that the flow becomes laminar is [Viscosity of water is 10^-3 N m^-1, take R_n = 200] ____________.

The colour of a star depends upon its ____________.

A solid sphere rolls down from top of inclined plane, 7m high, without slipping. Its linear speed at the foot of plane is ______. (g = 10 m/s²)

A solid sphere of mass 1 kg and radius 10 cm rolls without slipping on a horizontal surface, with velocity of 10 emfs. The total kinetic energy of sphere is ______.

The Reynold's number for a liquid flow in a tube does NOT depend on ______.

A man is supported on a frictionless horizontal surface. It is attached to a string and rotates about a fixed centre at an angular velocity `omega`. The tension in the strings is F. If the length of string and angular velocity are doubled, the tension in string is now ____________.

About black body radiation, which one of the following is 'WRONG' statement?

The power (P) is supplied to rotating body having moment of inertia 'I' and angular acceleration 'α'. Its instantaneous angular velocity is ______.

A ring and a disc roll on horizontal surface without slipping with same linear velocity. If both have same mass and total kinetic energy of the ring is 4 J then total kinetic energy of the disc is ______.

A solid sphere is rolling on a frictionless surface with translational velocity 'V'. It climbs the inclined plane from 'A' to 'B' and then moves away from Bon the smooth horizontal surface. The value of 'V' should be ______.

The angular velocity of minute hand of a clock in degree per second is ______.

Solid spherical ball is rolling on a frictionless horizontal plane surface about is axis of symmetry. The ratio of rotational kinetic energy of the ball to its total kinetic energy is ______.

If p is the density and η is coefficient of viscosity of fluid which flows with a speed v in the pipe of diameter d, the correct formula for Reynolds number R_e is ______.