Newton's First Law of Motion: Inertia and Forces
Science 8
Science 8
Chapter 2-The Laws of Motion
Chapter 2-The Laws of Motion
Newton’s First Law
Newton’s First Law
Lesson 2
Lesson 2
1.
1.
What causes an object in
What causes an object in
motion to remain in motion?
motion to remain in motion?
A.
friction
friction
B.
inertia
inertia
C.
gravity
gravity
D.
velocity
velocity
1.
1.
What causes an object in
What causes an object in
motion to remain in motion?
motion to remain in motion?
A.
friction
friction
B.
inertia
inertia
C.
gravity
gravity
D.
velocity
velocity
2.
2.
Extend
Three people push a
piano on wheels with forces of 130
N to right, 150 N to left, and 165 N
to the right. What are the strength
and direction of the net force on the
piano? Draw a diagram.
1
1
3
3
0
0
N
N
t
t
o
o
t
t
h
h
e
e
r
r
i
i
g
g
h
h
t
t
1
1
5
5
0
0
N
N
t
t
o
o
t
t
h
h
e
e
l
l
e
e
f
f
t
t
1
1
6
6
5
5
N
N
t
t
o
o
t
t
h
h
e
e
r
r
i
i
g
g
h
h
t
t
Force to the right—135 + 160 = 295 N to
the right
Force to the left = 150 N to the left
Net force= 145N to the right
Assess
Assess
A child pushes down on a
A child pushes down on a
box lid with a force of 25 N. At
box lid with a force of 25 N. At
the same time, her friend pushes
the same time, her friend pushes
down on the lid with a force of
down on the lid with a force of
30 N. The spring on the box lid
30 N. The spring on the box lid
pushes upward with a force of
pushes upward with a force of
60 N. Can the children close the
60 N. Can the children close the
box? Why or why not? Draw a
box? Why or why not? Draw a
diagram.
diagram.
Child
Child
pushes
pushes
down
down
25 N.
25 N.
Friend
Friend
pushes
pushes
down
down
30 N.
30 N.
The
The
spring on
spring on
the box
the box
pushes
pushes
60 N
60 N
upward.
upward.
25 N + 30 N
25 N + 30 N
?
?
60 N
60 N
25 N + 30 N < 60 N
25 N + 30 N < 60 N
No, the children can not push the lid
No, the children can not push the lid
down! Not enough force!
down! Not enough force!
Analyze
What is the missing force?
135 N ? N
Net force 25 N
Analyze
What is the missing force?
135 N ? N
Net force 25 N
135 N + ? N = 25 N
135 N + ? N = 25 N
110 N
110 N
To the left or -110 N
5.
5.
Use the information in the diagram to
Use the information in the diagram to
complete the equation and determine the net
complete the equation and determine the net
force on the object. The reference direction is
force on the object. The reference direction is
“to the right.”
“to the right.”
100 N 55 N
____________ N + _________________ N = _________________ N net force
5.
5.
Use the information in the diagram to
Use the information in the diagram to
complete the equation an determine the net
complete the equation an determine the net
force on the object. The reference direction is
force on the object. The reference direction is
“to the right.”
“to the right.”
100 N 55 N
100
100
N +
-55
-55
N =
45
45
N net force
Understanding the concept of inertia in motion, the role of forces in maintaining or changing motion, and analyzing net forces applied to objects. Also explores scenarios where forces are balanced or unbalanced, affecting the motion of objects.
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Presentation Transcript
Science 8 Chapter 2-The Laws of Motion Newton s First Law Lesson 2
1. What causes an object in motion to remain in motion? A. friction B. inertia C. gravity D. velocity
1. What causes an object in motion to remain in motion? A. friction B. inertia C. gravity D. velocity
2. Extend Three people push a piano on wheels with forces of 130 N to right, 150 N to left, and 165 N to the right. What are the strength and direction of the net force on the piano? Draw a diagram.
130 N to the right 130 N to the right 150 N to the left 150 N to the left 165 N to the right 165 N to the right
Force to the right135 + 160 = 295 N to the right Force to the left = 150 N to the left Net force= 145N to the right
Assess A child pushes down on a box lid with a force of 25 N. At the same time, her friend pushes down on the lid with a force of 30 N. The spring on the box lid pushes upward with a force of 60 N. Can the children close the box? Why or why not? Draw a diagram.
The spring on the box pushes 60 N upward. Child pushes down 25 N. Friend pushes down 30 N. 25 N + 30 N ? 60 N 25 N + 30 N < 60 N No, the children can not push the lid down! Not enough force!
Analyze What is the missing force? 135 N ? N Net force 25 N
Analyze What is the missing force? 135 N ? N Net force 25 N 135 N + ? N = 25 N To the left or -110 N 110 N
5. Use the information in the diagram to complete the equation and determine the net force on the object. The reference direction is to the right. 100 N 55 N ____________ N + _________________ N = _________________ N net force
5. Use the information in the diagram to complete the equation an determine the net force on the object. The reference direction is to the right. 100 N 55 N 100 N + -55 N = 45 N net force
