Whenever there is an interaction between two objects, there is a force upon each of the objects.

1. By Prof. Liwayway Memije-Cruz
All About Forces

2. Force
 any influence capable of producing a change
in the motion of an object.
 is a push or pull acting upon an object as a
result of its interaction with another object.
 Whenever there is an inte ractio n between two
objects, there is a force upon each of the
objects.
 When the inte ractio n ceases, the two objects
no longer experience the force.
Forces only exist as a result of an interaction.

4. Units of Force

6. Classification of Forces

7. Based on Line of Action
 forces that all go
through one point of
intersection.
 concurrent forces
can be added
together to obtain the
resultant. If the
forces are in
equilibrium, the
resultant will be zero.
Concurrent
Forces

8. Concurrent Forces: Tug of War
 If two people stand the ends of a rope and pull
on it, the forces are concurrent because the
effect of the forces will intersect at the same
point.

9. Non – concurrent Forces
 are two or more
forces whose
magnitudes are
equal but act in
opposite
directions with a
common line of
action.

10. Non-concurrent Forces: Cycling
 When a cyclist
pedals, his or her
feet are parallel.
One foot pushes a
petal forward while
the other pushes the
other pedal
backward. These
twoforces cause
the wheels on the
bike to rotate.

11. Coplanar Forces
 A set of points,
lines, line
segments rays
or any other
geometrical
shapes that lie
on the same
plane

12. Exercise
 Which of the
following
statements are
correct?
1. Points F, A, L, C, G, E,
O and B are coplanar.
2. Points G, E, F and A
are coplanar.
3. O, A and B are
coplanar.
4. Points F, A, L, I, C are
coplanar

13. Answer
A. 1 and
2 only
B. 3 and
4 only
C. 4 only
D. 1 only
1. a plane is a flat surface that extend in all
directions,
2. F, A, L, I, C lie on plane F, while G, E, O lie on
plane G so the first statement is false. A plane
can be named either by a single capital letter
or by naming at least three non-collinear
points in the plane.
3. Points G, E and F, A lie on two separate
planes, so statement 2 is false.
4. O and A lie on different planes…Third is false
5. F, A, L, I, C lie on the same plane. Fourth is
True.
Solution

14. Non-coplanar
 points which do not lie in the same plane or
geometrical plane.

15. Based on the Effects of Forces
 two forces acting in opposite
directions on an object, and
equal in size.
 Anytime there is a balanced
force on an abject, the object
stays still or continues moving
continues to move at the same
speed and in the same
direction.
 Balanced forces can be
demonstrated in Hanging,
Floating and Standing/sitting
objects.
Balanced Forces

16. Examples of Balanced Forces

17. Newton’s First Law of Motion
 An object at rest
stays at rest
and an object in
motion stays in
motion with the
same speed
and in the same
direction unless
acted upon by
an unbalanced
force.

18. Unbalanced Forces
 when two forces
acting on an object
are not equal in size.
 causes can cause:
a still object to move
a moving object to
speed up or slow
down
a moving object to
stop
a moving object to

19. Based on the intersection of
bodies.
 a force that acts
at the point of
contact between
two objects, in
contrast to body
forces.
Contact Forces

20.  the force of a
gravitational field
 the force of a
magnetic field
 the force of an
electric field
Non-contact
forces

21. Non-contact Forces

22. References:
 http://eschooltoday.com/science/forces/unbala
nced-forces.html
 http://www.physicsclassroom.com/Class/newtl
aws/U2l1d.cfm
 https://prezi.com/rybrk-acfh7h/types-of-
contact-and-non-contact-forces/
 https://www.reference.com/science/concurrent
-forces-physics-755bd4f9da9b8c9a