53) The ratio of kinetic energy and potential energy of a simple harmonic oscillator, at a displacement equal to half its amplitude is given by

54) A simple pendulum of length / has an energy E, when its amplitude is A. If the length of pendulum is doubled, the energy will be

55) Time period and length of a seconds pendulum respectively are

56) One end of an elastic string of natural length / and modulus X is kept fixed while to the other end is attached a particle of mass m which is hanging freely under gravity. The particle is pulled down vertically through a distance x, held at rest and then released.The motion is

57) A particle is executing simple harmonic motion in a line 1.0 m long. If the time of one complete vibration is 1 sec, then the maximum velocity of the particle is