CHAPTER NO 4
TURNING EFFECT OF FORCES
Q.1 explains the various
forces acting on a body?
Ans. (a) in the earth gravitation field, the attracts everything to
ward its center the gravitational force acting on each particle of body is parallel
as shown in fig (a)
(a)
In figure (b) two
a block is shown on a table. Two forces are acting on it. Its weight “w” in
downward direction while the normal force of the table on the block in an upward direction
these forces have some line of action and balance each other.
(b)
In figure “c” two
forces “p” and “Q” are shown which are acting at points “A” and “B” these
forces are known as parallel forces.
(c)
In figure (d) two
force “l” and “m” are shown which are acting at points “c” and “D” these forces
are known as “ anti-parallel” forces.
Q.2 Explain the addition of forces in detail:
Ans:-force is a vector quantity and forces can be added with each other by
vector algebra. The vector we get after the addition is known as the resultant vector.
Some special cases of the addition of vectors are given below.
1) When the angle
b/w forces are zero (Q=0). when the
angle b/w any two forces is zero then these vectors will be parallel to each
other in this case we add the magnitude of individual forces to get a magnitude
of resultant forces as shown.
2)
3) When angled/w forces are other than 00
4) Head to tail rules:- that method
in which we combine the tail of the 2nd vector with the head of 1st
vector and finally we combine the tail off is a vector is joined with the head of the last vector whose direction is toward the last vector and this is our resultant
vector this method of the edition of the vector is known as a head-tail rule.