Answer:
VB − VA = g tAB & (VA + VB)/2 = h / tAB
Explanation:
s = h = Displacement
tAB = t = Time taken
VA = u = Initial velocity
VB = v = Final velocity
a = g = Acceleration due to gravity = 9.8 m/s²




Hence, the equations VB − VA = g tAB & (VA + VB)/2 = h / tAB will be used
Given:
I=8A
t=2second
Potential difference,V=120-100=20volt
Workdone=V×i×t
=20×8×2
=320 joule.
I believe the answer is A) Less work in less time.
The period T of a pendulum is given by:

where L is the length of the pendulum while

is the gravitational acceleration.
In the pendulum of the problem, one complete vibration takes exactly 0.200 s, this means its period is

. Using this data, we can solve the previous formula to find L: