65) If the controlling force line for a spring controlled governor when produced intersects the Y-axis at the origin, then the governor is said to be

66) If the controlling force line for a spring controlled governor when produced intersects the Y-axis above the origin, then the governor is said to be unstable.

67) The product of the diametral pitch and module is equal to one.

68) The inversion of a mechanism is

69) The coefficient of fluctuation of energy is the ratio of maximum energy to the minimum energy.