This document discusses balanced and unbalanced forces and their effects on objects. It defines force as a push or pull and explains that forces have both size and direction, measured in Newtons. It states that when the sum of forces acting on an object equals zero, the forces are balanced, which results in no change in the object's velocity. However, if the sum is non-zero, the forces are unbalanced, which produces a change in the object's motion, such as its speed or direction. Examples of unbalanced forces include kicking a soccer ball or arm wrestling.

1. FORCES
“ A force to be reckoned with”

2. EQ: How do balanced and
unbalanced forces affect an
object?
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
S8P5.a – Recognize that every object exerts
gravitational force on every other object and
that the force exerted depends on how much
mass the objects have and how far apart they
are.
S8P3.b – Demonstrate the effect of balanced
and unbalanced forces on an object in terms of
gravity, inertia, and friction.

3. AS YOU ENTER…
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Look around the room and think about
the objects you see in terms of FORCE.
HINT: A force is always exerted by one
object to another object.
Answer the following:
Where do you see a force happening?
Which object is exerting the forces?
Which is receiving it?

4. Definition of FORCE
A push or pull
 EX:
- Using your fingers to pull open books
- Pushing buttons on a computer keyboard


5. FORCE

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Have both size and direction
Labeled in units called Newtons (N).
Two other concepts that have both size
and direction:
Velocity
Acceleration

6. DEFINITION OF NET FORCE

The combination all of the forces acting
on an object.

7. Determining the Net Force of
an object

When forces act in the
same direction, you add
the forces to determine
the net force. The net
force will be in the same
direction as the
individual forces.

8. Determining the Net Force of
an object

When two forces act in
opposite directions, you
subtract the smaller
force from the larger
force to determine the net
force. The net force will
be in the same direction
as the larger force.

9. Balanced Forces


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When the sum of the forces acting on any
object equal to zero, the forces are said to be
balanced.
Forces are balanced when they are equal in
size and opposite in direction.
NO CHANGE IN VELOCITY WHEN THE
FORCES ARE BALANCED! Constant speed!!!!

10. How is this picture an
Example of Balanced Forces?

11. Unbalanced Forces

Unbalanced forces occur when the sum of the
forces acting on any object is not equal to
zero.

Unbalanced forces produce a change in
motion, such as a change in speed or a change
in direction.

Unbalanced forces are necessary to cause a
nonmoving object to start moving.

12. Examples of Unbalanced
Forces


Soccer players kicking a soccer ball.
-Competing in an arm wrestling
competition against a world famous body
builder

13. THE BIG IDEA
 Unbalanced
forces cause
changes in motion that can
be predicted and described.

14. Bibliography

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
Motion basics. (1997). Retrieved from
http://www.physics4kids.com/files/motio
n_intro.html Force and motion facts.
(2013). Retrieved from
Force and motion facts. (2013).
Retrieved from
http://idahoptv.org/dialogue4kids/season
12/force_and_motion/facts.cfm/motion_i
ntro.html
Force. (2002). Retrieved from
http://library.thinkquest.org/CR0215468/f
orce_and_motion.htm