Transcript Newton`s 1st Law

Newton’s
st
1
Law
Final Review 2003
Terms…
• Inertia- The resistance an object has to a
change in its state of motion
• Velocity- Speed in a certain direction
• Mass- The quantity of matter
• Force- A vector quantity, producing motion in
the direction of its application; push or pull
• Equilibrium- When net force is zero
The Basic Concepts
• With no net force acting up on it…
- an object at rest tends to stay at rest
- an object in motion tends to stay in motion
- both objects will continue with same inertia and
same velocity
- as mass increases, inertia increases
Another Perspective
The Real World
-A car collision
•LAW OF INERTIA- the natural tendency of
an object to keep doing what its doing,
unless acted on by an unbalanced force
-resist changes in state of motion
•SEATBELTS?
The Truck and Ladder
•We experience inertia in vehicles when we brake or stop
More Examples
• Blood rushing from feet
to head when an elevator
going down stops
• Head-rests in cars to
prevent whip-lash
• Falling off a skateboard
• Sliding cloth out from
under objects
Unbalanced Forces & Friction
Galileo: If friction was eliminated
Inertia and Mass
• More mass=more
inertia
• Objects in motion
eventually stop due to
friction or other force
• Newton- force causes
objects to stop, not
move
Think about it…
• If you were on the
moon and you
threw a banana into
space, would the
banana A) gradually
stop due to air
resistance or B)
continue in motion
at a constant speed
in the same
direction?
• The answer is B…
- It would keep
going at a constant
speed in the same
direction due to
lack of gravity, air
resistance, or
friction.
Multiple Choice
• Which has more inertia?
A) Keiko
B) Hot air
balloon
C) Amazon Parrot
with a cracker
The answer is A because
Keiko has more mass
than the other two
object, therefore having
more inertia, or
resistance to change in
motion.
Almost Done
1) 1 kg= __ Newtons?
A) 1kg = 9.8 N
2) Does a 50 lb barbell
have twice as much
inertia and a 25 lb
barbell? Mass?
Volume? Weight?
A) All answers are YES