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

A uniform disc of radius ' a' and mass 'm' is rotating freely with angular speed 'ω' in a horizontal plane, about a smooth fixed vertical axis through its centre. A pa1ticle of mass 'm' is then suddenly attached to the rim of the disc and rotates with it. The new angular speed is ______

A particle starting from rest moves along the circumference of a circle of radius r with angular acceleration a. The magnitude of the average velocity, in the time it completes the small angular displacement θ is 

The length of solenoid is I whose windings are made of material of density D and resistivity p. The winding resistance is R. The inductance of solenoid is
[m = mass of winding wire, µ₀ = permeability of free space]

The radius of a soap bubble is blown up to double its value under isothermal conditions. If 'r' be the initial radius of the bubble, and T be the surface tension, then energy spent in doubling the radius is ______

Surface density of charge on a charged conducting sphere of radius R in terms of electric field intensity E at a distance r in free space is ____________.

(r > R, ε₀ = permittivity of free space)

A winding wire which is used to frame a solenoid can bear a maximum of 20 A current. If the length of the solenoid is 80 cm and its cross-sectional radius is 3 cm, then the required length of winding wire is ______ (B = 0.2 T)

A toroid has a core (non-ferromagnetic) of inner radius 25 cm and outer radius 26 cm, around which 2,000 turns of a wire are wound. If the current in the wire is 10 A, the magnetic field inside the core of the toroid will be ______

The moment of inertia of a uniform thin rod of length L and mass M about an axis passing through a point at a distance of L/3 from one of its ends and perpendicular to the rod is ______

A ball is thrown vertically down from height of 80 m from the ground with an initial velocity 'v'. The ball hits the ground, loses `1/6`th of its total mechanical energy, and rebounds back to the same height. If the acceleration due to gravity is 10 ms^-2, the value of 'v' is

Three points masses, each of mass m are placed at the corners of an equilateral triangle of side l. The moment of inertia of the system about an axis passing through one of the vertices and parallel to the side joining other two vertices, will be ______.

If radius of the solid sphere is doubled by keeping its mass constant, the ratio of their moment of inertia about any of its diameter is ______.

Given that 'p' joule of heat is incident on a body and out of it 'q' joule is reflected and transmitted by it. The absorption coefficient of the body is ____________.

A ball moving with velocity 5 m/s collides head on with another stationary ball of double mass. If the coefficient of restitution is 0.8, then their velocities (in m/s) after collision will be ____________.

Two rods, each of mass m and length l, are joined as shown in the figure. Moment of inertia of system about an axis passing through one end of the rod, i.e. O, and perpendicular to the plane is ____________.

Energy needed in breaking a drop of radius R into n drops each of radius r is given by ____________.

Each plate of a parallel plate condenser has surface area of 5 cm². The distance between the plates is 2 mm. The dielectric constant of the medium between the plates is 5. Then the capacity of the condenser is ____________.

(`epsilon_0 = 8.85  xx 10^-12 C^2//Nm^2`)

Assertion: If work done in increasing the size of a soap film from 10 cm x 4 cm to 10 cm x 8 cm is 2 x 10^-4 J, then the surface tension is 5 x 10^-4 N m^-1.

Reason: Work done = Surface tension x increase in area.

If two identical mercury drops are combined to form a single drop, then its temperature will ____________.

Four solid spheres each of mass M and radius R are placed with their centres on the four comers of a rectangle. If b is a breadth of rectangle and its length is twice of its breadth, then find moment of inertia of the system about an axis along one of the breadth of the rectangle.

In Rutherford experiment, for head-on collision of a-particles with a gold nucleus, the impact parameter is ______.