472 - Physics Questions Answers

small ring is threaded on an inextensible frictionless cord of length 2l.

The ends of the cord are fixed to a horizontal ceiling. In equilibrium, the  

ring is at a depth h below the ceiling. Now the ring is pulled aside by a  

small distance in the vertical plane containing the cord and released.  

Find period of small oscillations of the ring. Acceleration of free fall is g.

Find potential energy of disc having charge density sigma uniformly distributed on its surface,radius R

A small metal ball is being pulled gradually on a fixed frictionless hemisphere as shown in the figure. Radii of the ball and that of the pulley are much smaller than that of the hemisphere. As the ball slides from the bottom to a position close to the top of the hemisphere, how do the magnitudes of pulling force F and contact force R between the ball and the hemisphere change?

(a) F increases and R decreases.

(b) F decreases and R increases.

(c) F decreases and R remains unchanged.

(d) F remains unchanged and R decreases.

Three identical balls are placed on a frictionless horizontal surface touching each other. They stick to each other because of adhesive. Another ball of same radius and mass m is placed on the void created by the three balls. Find the forces applied by the balls kept on the floor to each other if the system remains in equillibrium.

There are N numbers of electrons present in a one-dimensional box of length L. Assuming no coulombic interactions are present, find the ground-state energy of the N-particle system. N is an even number and mass of each electron is m. All electrons have a definite momentum, p, and their collisions with the box are perfectly elastic.

Sir 

Does time exist or is it just an illusion .

Please tell.