The tension has to hold the part of the weight in the direction of the string:
T = mg*cos(theta)
Theta=0, whole weight, theta=90, T=0, if the pendulum is horizontal, the string will be loose! Yeah
Answer:
Here is the complete question:
https://www.chegg.com/homework-help/questions-and-answers/magnetic-field-372-t-achieved-mit-francis-bitter-national-magnetic-laboratory-find-current-q900632
a) Current for long straight wire 
b) Current at the center of the circular coil 
c) Current near the center of a solenoid 
Explanation:
⇒ Magnetic Field due to long straight wire is given by (B),where

Plugging the values,
Conversion
,and 

⇒Magnetic Field at the center due to circular coil (at center) is given by,
So 
⇒Magnetic field due to the long solenoid,
Then
So the value of current are
,
and
respectively.
Answer:
426.84 m
Explanation:
initial velocity u = 0
time t = 3.3 s
distance travelled s = 53.4 m
acceleration due to gravity = g
s = ut + 1/2 g t²
53.4 = 0 + 1/2 g x 3.3²
g = 9.8 m /s²
For the whole length of fall
distance travelled = h
total time = 6.6 + 3.3 = 9.9 s
h = ut + 1/2 g t²
u again = 0
h = .5 x 9.8 x 9.9²
= 480.24 m
distance travelled in last 6.6 s
= 480.24 - 53.4
= 426.84 m
A flat line means the the speed is the same . Its moving at the same pace.