We can assume that all gravitational potential energy is converted into kinetic energy of the object.
Hence, GPE = KE
Where GPE is gravitational Potential Energy (J) and KE is Kinetic Energy (J)
GPE = mgh
Where, m is the mass of the object (kg), g is acceleration due to gravity (9.8 m s⁻²) and h is the height to the object from ground (m).
m = 0.18 kg
g = 9.8 m s⁻²
h = 45 m
Hence,
GPE = 0.18 kg x 9.8 m s⁻² x 45 m
= 79.38 J
≈ 79 J
Hence, KE = GPE = 79 J
Hence, the answer is '79 joules'.