1. Balanced & Unbalanced Forces
Created by Kesler Science – More 5E lessons at KeslerScience.com
Presented by Kesler Science

2. Essential Questions: What are balanced and unbalanced forces?
How do unbalanced forces cause a change in position, direction, and speed of an object when acted upon by unbalanced forces?

3. Balanced and Unbalanced Forces
A push or a pull that causes an object to stop, move, or change direction.
Forces push downward toward the Earth’s center (gravity) or push upward on an object (normal or supporting force).
Forces may or may not cause movement.
Ex. 1 – A book pushes down on a table while the table pushes up on the book.
Ex. 2 – A car accelerates(changes speed and direction)causing motion.
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4. Forces Template Quick Action – Forces INB Template
Cut out the Balanced, Unbalanced, Net Force template.
Fold along the dashed lines.
Glue it to your journal along the skinny tab.
Define each term.
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5. Balanced and Unbalanced Forces
Two forces equal in size
and acting in opposite
directions on an object.
The object stays still or
continues to move at the
same (constant) speed and in the same direction.
Students understand the concept of balanced forces being at rest, but struggle to grasp the concept that forces are balanced if the object continues moving at the same speed and in the same direction.
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6. Balanced Forces Examples
Balanced and Unbalanced Forces
Balanced Forces Examples
At rest
At rest
At rest
At a constant speed and same direction
At a constant speed and same direction
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7. Unbalanced Forces Balanced and Unbalanced Forces Always cause a
Two forces that are unequal in size and opposite in direction.
Always cause a
change in motion in
one of these areas:
position
direction
speed
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8. Unbalanced Forces Examples
Balanced and Unbalanced Forces
Unbalanced Forces Examples
Horse #2 is stronger
20N
Moves Left
10N
The student exerting the strongest force will determine the direction of movement.
Changing directions
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9. Which way will they move?
Balanced and Unbalanced Forces
Net Force 
The overall forces acting
on an object.
Measured in Newtons (N)
Net Force1N 3N 2N
Which way will they move?
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10. Quick Action – Demonstrate Forces
Choose a partner for this activity. The teacher will number off the pairs.
Even numbered pairs will come up with an example of a balanced force, which they will present to the class.
3. Odd numbered pairs will come up with an example of a unbalanced force, which they will present to the class. (Use examples of changing either position, speed or direction)
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11. Quick Action – Balanced or Unbalanced Template
Cut out the template
Fold the flaps away from the side that says “Glue this side down”
Glue it to your journal on the hexagon side that says “Glue this side down”
Answer “balanced” or “unbalanced” under each flap.
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12. Balanced and Unbalanced Forces
How do unbalanced forces cause a change in position of an object?
A skier is at the top of a hill
(balanced force). Another skier
bumps him (unbalanced force)
causing him to fall down.
This unbalanced forced caused
his position to change.
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13. Balanced and Unbalanced Forces
How do unbalanced forces cause a change in direction of an object?
A skier is at the top of a hill
(balanced force). Then then the
skier decides to point her skis
down the hill and push off
(unbalanced force).
This unbalanced force causes her
a change in direction.
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14. Balanced and Unbalanced Forces
How do unbalanced forces cause a change in speed of an object?
A skier is at the top of a hill
(balanced force) at the
beginning of a race. As he flies
down the mountain (unbalanced
force) he picks up speed.
This unbalanced force causes him
a change in speed.
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15. Check for Understanding
Can you…
1. Describe balanced and unbalanced forces?
2. Identify and describe how unbalanced forces cause a change in position, direction, and speed of an object when acted upon by unbalanced forces?
Clear up any confusion and answer questions.
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