Force-and-Motion.pdf
Acting
Liberty University (LU)
16 pag.
Force
&
Motio
n
Inertia
Inertia
is the tendency of an object to keep
doing what it is doing
• An object at rest will remain at rest
until acted upon by an unbalanced
force.
• An object in motion will remain in
motion until acted upon by an
unbalanced force.
How Can Balanced Forces
Affect Objects?
• Cause the shape of an object to change
without changing its motion
• Cause an object at rest to stay at rest or an
object in motion to stay in motion (inertia)
• Cause an object moving at a constant speed
to
continue at a constant speed
What is an
example of a
balanced
force?
How Can Unbalanced Forces
Affect Objects?
• Acceleration is caused by unbalanced forces:
– slow down
– speed up
– stop
– start
– change direction
– change shape
What is an
example of a
unbalanced
force?
Net Force
The Net
force
is he total of all forces
acting on an object:
– Forces in the same direction are added.
• The object will move in the direction of the
force.
– Forces in opposite directions are
subtracted.
• An object will move in the direction of the
greater force.
Calculating Net Force
30 N 10 N
http://commons.wikimedia.org/wiki/File:Jack-in-the-box.jpg
A child was playing with a jack in the box. The lid
pushed down with 10 N of force, while the spring
pushed up with 30 N of force. What is the net force
applied by the spring?
In your notebook, calculate the net force and show
all of your work.
Check Your Answer
30 N 10 N
http://commons.wikimedia.org/wiki/File:Jack-in-the-box.jpg
A child was playing with a jack in the box. The lid
pushed down with 10 N of force, while the spring
pushed up with 30 N of force. What is the net force
applied by the spring?
30 N up - 10 N down= 20 N up
Calculating Net Force
30 N
Tug of
War
Game 50 N
Two competitors are playing tug of war.
What is the net force? Which direction will the rope
move?
In your notebook, calculate the net force and show
all of your work.
Mass and Weight
•Mass is the amount of stuff (matter) in an object.
– The mass of an object will remain the same
anywhere in the universe.
– Mass is measured in grams or kilograms.
•Weight
is the mass (kg) of an object multiplied by
(x) the acceleration of gravity (9.8 m/s2).
– The weight of an object depends on the gravitational
pull at the location in the universe.
– Weight is measured in newtons (N).
