Answer:
B
Explanation:
The control is something that is meant to not be changed, the control is a comparison of the experimental.
Answer:
Part a)

Part b)

Explanation:
As we know that torque is defined as the product of force and its perpendicular distance from reference point
so here we have

now we have


Part b)
Now we know the conversion as
1 meter = 3.28 foot
1 N = 0.225 Lb force
now we have



Odd though it seems at first, gravity is pulling the cat down while the floor is pushing the cat up - in equal amounts. Forces are absolutely acting on the cat but they balance - so there is no net force.
To develop this problem it is necessary to apply the concepts related to a magnetic field in spheres.
By definition we know that the magnetic field in a sphere can be described as

Where,
a = Radius
z = Distance to the magnetic field
I = Current
Permeability constant in free space
Our values are given as
diameter of the sphere then,

Thus z = a



Re-arrange to find I,



Therefore the current at the pole of this sphere is 