Answer:
149.8Hz
Explanation:
V=I.(XL).........{1}
where (XL) is inductive reactance
(XL) =2πfL......... {2}
V= 41.5, l= 4.5, L= 9.8* 10^-³
take π to be 3.14
(XL) = V/I
= 41.5/4.5
= 9.22
f = (XL) /2πL
= 9.22* 10^³/6.28* 9.8
=149.8
Friction, gravity, normal force, and the brakes constitute an applied force.
The period of a simple pendulum is given by:

where L is the length of the pendulum and g is the gravitational acceleration.
The pendulum in our problem makes one complete vibration in 0.333 s, so its period is T=0.333 s. Using this information, we can re-arrange the previous formula to find the length of the pendulum, L: