Answer:
Case A
Explanation:
given,
size of bacteria = 1 mm x 1 mm
velocity = 20 mm/s
size of the swimmer = 1.5 m x 1.5 m
velocity of swimmer = 3 m/s
Viscous force

for the bacteria


for the swimmer


from the above force calculation
In case B inertial force that represent mass is more than the inertial force in case of bacteria.
Viscous force is dominant in case of bacteria.
So, In Case A viscous force will be dominant.
Answer:
A. 3.4 m
Explanation:
Given the following data;
Force = 56.7N
Workdone = 195J
To find the distance
Workdone is given by the formula;
Making "distance" the subject of formula, we have;

Substituting into the equation, we have;

Distance = 3.4 meters.
Answer:
D.) All people can mate with one another and have children
Explanation:
A. To find work we need to know F and S; to find power we need to know F and V
Answer:

and

Explanation:
See attached figure.
E due to sphere
E due to particule
(1)
according to the law of gauss and superposition Law:
; electric field due to the small sphere with r1=R/4


then:
(2)
on the other hand, for the particule:

⇒
(3)
We replace (2) y (3) in (1):


--------------------
if R<x<2R AND 

remember that 
then:

solving:


but: R<x<2R
so : 