Answer:
Approximately
. (Assuming that
, and that the tabletop is level.)
Explanation:
Weight of the book:
.
If the tabletop is level, the normal force on the book will be equal (in magnitude) to weight of the book. Hence,
.
As a side note, the
and
on this book are not equal- these two forces are equal in size but point in the opposite directions.
When the book is moving, the friction
on it will be equal to
, the coefficient of kinetic friction, times
, the normal force that's acting on it.
That is:
.
Friction acts in the opposite direction of the object's motion. The friction here should act in the opposite direction of that
applied force. The net force on the book shall be:
.
Apply Newton's Second Law to find the acceleration of this book:
.
Answer: 2 diodes
Explanation:
Given : In proof testing of circuit boards, the probability that any particular diode will fail is 0.01.
The number of diodes contained by circuit board = 200
Then , the expected number of diodes to fail is given by :-

Therefore, there are 2 diodes that we will expect to fail.
Answer
given,
Tension of string is F
velocity is increased and the radius is not changed.
the string makes two complete revolutions every second
consider the centrifugal force acting on the stone
=
now centrifugal force is balanced by tension
T =
From the above expression we can clearly see that tension is directly proportional to velocity and inversely proportional to radius.
When radius is not changing velocity is increasing means tension will also increase in the string.