Not sure the precise concept of "normal observation", but I assume that is observed by "eyes".
Eye observation is basically macroscopic, but when you use a mark, which can be regarded as a point of mass, then it goes to microscopic.
Mark is a reference point which you can compare the relative position change, but with your eyes, first you cannot notice microscopic changes, second the eyes cannot precisely set a stable reference point.
As per the question, the resistor system contains two resistors.
The two resistors are denoted as 
We are asked to calculate the effective resistance in terms of
The two resistors can be connected in two ways.
CASE-1: Let the resistors are connected in series.
When the resistors are connected in series, the effective resistance is the algebraic sum of the individual resistors.
Hence, the effective resistance 
[ans]
CASE-2: Let the resistors are connected in parallel.
The effective resistance is calculated as follows-
⇒ 
[ans]
Answer:
<h2>C) internal combustion engine</h2>
Explanation:
Answer:
Angular acceleration = -1.57 Rad/s^2
Number of revolutions = 800 revolutions
Explanation:
Mass = 1.15kg
diameter of the grinding wheel = 22.0cm
angular speed = 20 rev/s
1 Rev/s = 6.283 rad/s
20 Rev/s = 20 * 6.283 = 125.664 rad/s
Angular acceleration = Angular speed/ time taken for for the wheel rotation
Angular accleration = 125.664/80
Angular acceleration = -1.57 rad/s^2 (since the wheel is rotating counterclockwise)
number of revs = 0.5∝t²
number of revs = 0.5 * (1.57/2π) * 80²
number of revs = 800 revolutions
Answer: 51N
Explanation: T = mv^2/r 51 = 76v^2/1.3 v =.934
