Answer:
T = 0.017s
Explanation:
period is the time it takes a particle to make one oscillation
An electric current is periodic in nature
The current reaches 3.8A ten times.
So there must have been 10 cycles (10 periods) in 0.17s. let 'T' be the period:

t is the total time interval
n is the number of oscillations

10T = 0.17
T = 0.17/10 = 0.017s
Umm... I think I saw this question somewhere else answered.... You should look for it.
I'm not sure. But it can be A or C.
We will assume that the CM of the arm is at "L"
from the elbow, and the ball is at 34cm. Then the net torque is computed
by:
Net τ = 1.42 N * 34 cm + 1.50 kg * 9.8m/s² * 34 cm/2 – 12.6 N*2.75cm
= 48.28 N*cm + 1.50kg * 9.8m/s² * 34 cm/2 – 12.6 N*2.75cm
= 48.28 N*cm + 499.8 – 34.65 N*cm
τ = 513.43 N*cm or
5.1343 N*m