Statement (a) is correct. An object is raised to a height of 3 m from the ground. It is then allowed to fall on to a table 1 m high from the ground level. Total energy at 3 m = potential energy at 3 m + kinetic energy at 3 m Potential energy at 3 m = mass × g × 3 Kinetic energy at 3 m = 0 Total energy at 3 m = 3 mg + 0= 3 mg Total energy at 1 m = potential energy at 1 m + kinetic energy at 1 m Potential energy at 1 m = mass × g × 1 Kinetic energy at 1 m = 0 Total energy at 1 m = 1 mg + 0= 1 mg Hence, potential energy at 1 m decreases by two-thirds its original value of total energy.