A train of 150 m length is going towards north direction at a speed of 10 ms-1 A parrot flies at a speed of 5 ms-1 towards south direction parallel to the railway track,The time taken by the parrot to cross the train is equal to
What will be the duration of the day and night (in hour) if the diameter of the earth is suddenly reduced to half its original value the mass remaining constant?
A monochromatic source of light is placed at a large distance d from a metal surface. Photoelectrons are ejected at rate n, kinetic energy being E. If the source is brought nearer to distance d/2, the rate and kinetic energy per photoelectron become nearly