Transcript Newton`s 3 Laws of Motion - Franklin Regional Middle School

Newton’s 3 Laws
of Motion
Newton’s first Law
The Law of Inertia
• An object Stays in the
state of rest or motion
unless acted on by
another force
• This law explains why a driver is thrown
forward in a head-on automobile
accident. The car may have stopped,
but the driver continues moving forward
unless held in place by a seatbelt.
Newton’s
nd
2
Law
The Law of Acceleration
• When a force acts on
an object, the object
will accelerate
proportionally to the
force and in the same
direction.
• To understand this law, imagine
pushing a pebble, and then imagine
pushing a boulder.
• The pebble has a smaller mass, and
so it will accelerate faster than the
boulder if the force is the same .
Vs.
• Now imagine pushing a boulder with
your bare hands and then imagine
pushing it with a powerful backhoe.
• The backhoe is able to exert more
force on the boulder, and it will make
it accelerate faster than when you
pushed it with your bare hands.
Vs.
As long as the force remains constant,
an object with a smaller mass will
accelerate faster.
AND
As long as the mass remains
constant, acceleration will be faster
with a greater force.
Newton’s
rd
3
Law
The Law of Interaction
• For every
action, there
is an equal
and opposite
RE-Action.
•A baseball is
thrown towards
the batter at a
certain force.
•The batter then
places the bat
in the path of
the ball.
• The Ball hits
the Bat in the
direction it
was thrown.
•The force is
returned equally
in the opposite
direction by the
bat.
•This causes the
ball to travel into
the playing field.
•Why do some
balls travel
farther then
others?
Newton’s Collisions - Example #1
• Two bumper cars are in a high velocity head-on
collision. Each car has a mass of 300 kg.
• The red car has a person with a mass of 25 kg.
The red car is at rest.
• The green car has a person with a mass of 75 kg.
What’s going to happen?
A
B
• Because the red car was sitting still and was
hit by a car traveling at a high rate of speed
with a driver three times the mass, the red
car will experience the greatest change in
position.
• After the collision, the red car will move off
with the green car in the direction the green
car was moving.
Newton’s Collisions - Example #2
• Two bumper cars are in a glancing collision.
Each car has a mass of 300 kg.
• The red car has a person with a mass of 90 kg.
• The green car has a person with a mass of 45
kg.
• Both cars are traveling at the same velocity.
What’s going to happen?
A
B
• The driver of the red car has twice the mass of
the driver of the green car, and they are traveling
at the same speed.
• When they collide, the red car will slow down and
the green car will speed up.
• They will both be deflected from their original
path, but the red car will be deflected less than
the green car because of the greater mass.
Newton’s Collisions - Example #3
• Two bumper cars are in a head-on collision.
Each car has a mass of 300 kilograms.
• The red car has a person with a mass of 70 kg.
• The green car has a person who also has a
mass of 70 kg.
• The red car has a velocity twice that of the
green car.
What’s going to happen?
A
B
• In this head-on collision with cars of equal
masses, the red car will end up exchanging
velocities with the green car.
• This will cause the green car to be deflected at
a greater velocity than the red car.
• Both cars will be deflected back along their
previous paths.