Physics Test 22...

A particle is projected with velocity v₀ along x-axis. A damping force is acting on the particle which is proportional to the square of the distance from the origin i.e. ma = -ax². The distance at which the particle stops:

Two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below. 

Assertion(A) :

The photoelectrons produced by a monochromatic light beam incident on a metal surface have a spread in their kinetic energies.  

Reason(R) :  

The energy of electrons emitted from inside the metal surface, is lost in collision with the other atoms in the metal.

A rod of length L revolves in a horizontal plane about the axis passing through its center and perpendicular to its length. The angular velocity of the rod is ω. If A is the area of cross-section of the rod and ρ is its density, then the rotational kinetic energy of the rod is

Which of the following is not correct about the first law of thermodynamics:

Two particles of equal mass m have respective initial velocities They collide completely inelastically. The energy lost in the process is :

A particle of mass 'M' moves along a straight line and collides with a stationary point mass 'm' such that they follow the same straight-line path​. The collision is elastic and the ratio of the final velocities of M and m​ is x. If m = 0.5M, the value of x is -

One end of a metal wire is fixed at the centre of a uniform disc of radius 4.0 cm and mass 100 g. The other end of the wire is fixed with a clamp. The hanging disc is rotated about the wire through a small angle and is released. If the disc makes torsional oscillations with time period 0.20 s, the torsional constant of wire is (Given π² = 10)

The equation of motion of a particle is x = a cos (α t)².

The motion is

Two satellites A and B of masses 200 kg and 400 kg are revolving round the earth at height of 600 km and 1600 km respectively.

If T_A and T_B are the time periods of A and B respectively then the value of T_B - T_A :

[Given : radius of earth = 6400 km, mass of earth = 6 × 10²⁴ kg]

In an experiment on the specific heat of a metal, a 0.30 kg block of the metal at 120 °C is dropped in a copper calorimeter (of water equivalent 0.025 kg) containing 100 cm³ of water at 27 °C. The final temperature is 35 °C. Calculate the specific heat of the metal?