Answer:
Work done by firefighter = 13456.57 J
Step-by-step explanation:
Here work done is equal to potential energy gained by him.
Potential energy, PE = mgh, where m is the mass, g is acceleration due to gravity value and h is the height.
Mass, m = 64.4 kg
Acceleration due to gravity, g = 9.8 m/s²
Height, h = 21.3 m
Substituting
Potential energy, PE = mgh = 64.4 x 9.81 x 21.3 = 13456.57 J
Work done by firefighter = 13456.57 J