Correct Answer - Option 4 :
4 m
Concept:
Moment is the product of force multiplied by the moment arm length.
Moment = Force × (moment arm length)
Calculation:
Given:
Force = 16 N, moment = 64 Nm
Moment arm length = 64/16 m
Moment arm length = 4 m
Hence, the length of moment arm is 4 m.