Forces Notes
“Any influence that can cause a body tobe.
It is measured in.”
A is the force needed to accelerate one kg one meter per second per second
A or exerted by an object to/on another object
Always occurs in (Sometimes referred to as Agent & Receiver)
It can alter the or of an object
It is represented by that show and size
DemosWhat it demonstrates
Rolling Ball
Pushing a closed door
Standing on the floor
Clay ball
Tennis ball
Pushing on a table
Newton’s Laws of Motion
Law #1:
“Every body continues in its state
of , or of
uniform motion in a straight line,
unless it is compelled to that state
by forces impressed upon it.”
Sometimes called the Law of
What is Inertia?
“The sluggishness or apparent
a body offers to changes in its state of motion”
The larger the, the larger its
A body with less is easier to get moving
A body with more mass is to get moving
DemosWhat it demonstrates
Ping pong ball
Bowling ball
Granny
Mack Truck driven by Granny
Mass
Defined as “The quantity ofin a body”
It is the measurement of
m = mass; F = force; a = acceleration
= F/a
= m(a)
= F/m
Momentum
The product of and
It is in motion
DemosWhat it demonstrates
Car on a ramp
Eeyore on a car on a ramp
Conservation of Momentum
All energy stored in a moving object is not, but only form
Stated by:
DemosWhat it demonstrates
Newton’s Cradle
Swinging Rock
Mass in a Circular Motion
When an object moves in circular path, it has a property called Inertia
AKA: Inertia
“An object rotating about an tends to remain rotating about that same axis unless it is interfered with by some external force.”
This definition is similar to Newton’s
DemosWhat it demonstrates
Bicycle tire
Gyroscope
Top
Frisbee
Football
Moment of Inertia
Angular Momentum
It is a measure of an object’s rotation
about a particular
For an object small compared to the radial distance, it is
the product of mass, velocity and radius ( x x )
It is the measure of the rotational property
of
It is to
the centripetal force
DemosWhat it demonstrates
Rolling objects
Washer on a string
Slingshot (old-fashioned!)
Bucket with water spun in vertical circles
Q: What holds the water in the bucket?
Spin cycle of washing machine
“Whizzer”
Brendan on the Scrambler
Carnival Ride Know-How
It’s better to take the seat
of the car if you’re riding alone
If you’re riding with someone
else, take the seat
The following formula is similar to those
for Newton’s, but
deals with mass in motion in a circular path: mvr = mvr
m =
v =
r =
What happens in this situation?
mvr = mvr
… The mass is not affected by a smaller radius, while is.
Centripetal Force
A center-seeking that causes an object to follow a circular path.
“Any force that is directed at to the path of the moving body and produces circular motion.”
Name the centripetal force that keeps the moon
revolving around the earth:
Centrifugal Force
A fictitious force
due to rotation
It is a to centripetal
force but there is no agent, therefore it is experienced
relative to position
What we are really experiencing is!
Newton’s Second Law
The acceleration of a body is proportional to the net force acting on the body and proportional to the mass of the body and is in the direction of the NET
Formulas:
= F/m
= m (a)
= F/a
Newton’s Third Law
Whenever one body exerts a on a second body, the
second body exerts an and opposite force on the first
For every, there is an equal and opposite reaction
You cannot without being
Common Forces
Gravitational – non contact
Every object exerts an force on every other object
Buoyancy - contact
The tendency to in a fluid
Friction - contact
The to motion where two objects touch
Magnetic – non contact
The repelling or of a magnet and ferromagnetic material
Elastic - contact
Ability to to its original size, shape, or position after being stretched, squeezed, flexed, expanded, etc.
Electrical – non contact
Flow or gathering of a negative charge by
Other Physics concepts of interest:
Energy
The quality of an object that enables it to do
Power
Work/ Time
Potential Energy
The energy that a body
possesses because of its position with respect to other bodies
Kinetic Energy
The energy of
Kinetic Energy = 1/2 mv2