Balanced and Unbalanced Forces
What is a force?

A force is a push or pull that causes an object to
move, stop, or change direction

In physics a force is anything that makes an object
accelerate
Force
Forces come in pairs
 Forces have a magnitude and a
direction

5N, north (up)

Magnitude: 5N
Direction: north (up)
1 N (Newton) = 1 kg * m/s/s
Balanced and Unbalanced Forces

Forces occur in pairs and they can be
either balanced or unbalanced
Balanced Forces
Balanced forces do not cause change
in motion
 They are equal in size and opposite in
direction

Unbalanced Forces

An unbalanced force always causes a
change in motion

When unbalanced forces act in opposite
directions you can find the net force

Net force

Magnitude


The difference between the two forces
Direction

Direction of the largest force
Unbalanced Forces
3 N, right – 6 N, left = 3N, left
Unbalanced Forces
4 N, left – 10 N, right = 6N, right
Unbalanced Forces
5 N, right + 10 N, right =15N, right
Video Quiz- (6 Questions)
1. The Scientist who devised the 3 laws
of motion was:
A) Isaac Newton
B) Albert Einstein
C) Charles Darwin
D) Thomas Edison
Video Quiz
2. The first law of motion states that if all
the forces acting upon an object are
BALANCED, then there will be:
A) acceleration
B) the object stopping
C) no acceleration
D) deceleration
Video Quiz
3. No acceleration means:
A) increasing velocity OR the object is
stationary
B) constant velocity OR the object is
stationary
C) decreasing velocity OR the object is
stationary
Video Quiz
4. The size of the force of gravity is an
object's:
A) density
B) mass
C) weight
D) chemical structure
Video Quiz
5. When forces are BALANCED on an
object, the object will either:
A) decelerate OR accelerate
B) start moving OR decelerate
C) stop moving OR travel at a constant
velocity
D) remain stationary OR travel at a
constant velocity
Video Quiz
6. When forces are UNBALANCED on an
object, the object will either:
A) remain stationary OR travel at a
constant velocity
B) accelerate OR decelerate
C) start moving OR travel at a constant
velocity
D) stop moving OR travel at a constant
velocity
Video Quiz- (6 Questions)
1. The Scientist who devised the 3 laws
of motion was:
A) Isaac Newton
B) Albert Einstein
C) Charles Darwin
D) Thomas Edison
Video Quiz
2. The first law of motion states that if all
the forces acting upon an object are
BALANCED, then there will be:
A) acceleration
B) the object stopping
C) no acceleration
D) deceleration
Video Quiz
3. No acceleration means:
A) increasing velocity OR the object is
stationary
B) constant velocity OR the object is
stationary
C) decreasing velocity OR the object is
stationary
Video Quiz
4. The size of the force of gravity is an
object's:
A) density
B) mass
C) weight
D) chemical structure
Video Quiz
5. When forces are BALANCED on an
object, the object will either:
A) decelerate OR accelerate
B) start moving OR decelerate
C) stop moving OR travel at a constant
velocity
D) remain stationary OR travel at a
constant velocity
Video Quiz
6. When forces are UNBALANCED on an
object, the object will either:
A) remain stationary OR travel at a
constant velocity
B) accelerate OR decelerate
C) start moving OR travel at a constant
velocity
D) stop moving OR travel at a constant
velocity