#### Transcript Slide 1

```Forces
You will be able to:
● Identify and describe the changes in
position, direction, and speed of an object
when acted upon by unbalanced forces.
● Identify balanced and unbalanced forces.
Adapted from a PowerPoint by Kathleen Ingram, Lamar Middle School
What are some common forces?
Gravity – the force with which the earth, moon,
or another massive object attracts another
object towards itself.
What are some common forces?
Normal force – a support force exerted upon
an object in contact to another object.
Net Force
The net force is the combined effect of all
forces acting on an object.
Force
Balanced Forces
 forces acting on an
object that are
opposite in direction
and equal in size
 no change in speed
Force
Unbalanced forces
 unbalanced forces that are not opposite and
equal
 velocity changes (object accelerates)
Fnet
Ffriction
Fpull
N
N
W
Are there different forces acting on the figure skaters?
What direction are the forces acting?
Are the forces balanced or unbalanced? How do you
know?
Balanced and unbalanced forces
http://www.engineeringinteract.org/resourc
es/parkworldplot/flash/concepts/balanced
andun.htm
Today we will demonstrate…
(A) basic relationships between force and
motion using simple machines including
pulleys and levers
(A) that an object will remain at rest or move
at a constant speed and in a straight line
if it is not being subjected to an
unbalanced force
(B) how unbalanced forces cause changes in
the speed or direction of an object's
motion
Tug of War
 drawing
Force Problems
20 N
20 N
What is the net force?
Are the forces balanced or unbalanced?
Describe the motion of the object. (none, accelerate to
left, accelerate to right)
Force Problems
20 N
30 N
What is the net force?
Are the forces balanced or unbalanced?
Describe the motion of the object. (none, accelerate to
left, accelerate to right)
Force Problems
20 N
10 N
What is the net force?
Are the forces balanced or unbalanced?
Describe the motion of the object. (none, accelerate to
left, accelerate to right)
Force Problems
20 N
30 N
What is the net force?
Are the forces balanced or unbalanced?
Describe the motion of the object. (none, accelerate to
left, accelerate to right)
Force Problems
30 N
30 N
What is the net force?
Are the forces balanced or unbalanced?
Describe the motion of the object. (none, accelerate to
left, accelerate to right)
```