Newton’s First Law
Newton’s First Law
An object at rest
_____________,
And an object in motion
___________________,
Until acted on by
______________.
Newton’s First Law
An object at rest
remains at rest,
And an object in motion
___________________,
Until acted on by
______________.
Newton’s First Law
An object at rest
remains at rest,
And an object in motion
remains in motion,
Until acted on by
______________.
Newton’s First Law
An object at rest
remains at rest,
And an object in motion
remains in motion,
Until acted on by
an unbalanced force.
Why does the ladder fly off?
The ladder is an object in motion.
An object in motion remains in motion,
until acted on by an unbalanced force.
Why does the driver fly out?
The driver is an object in motion.
An object in motion remains in motion until
acted on by an unbalanced force.
How does this magic trick work?
• The plates and cups
are objects at rest.
• Objects at rest remain
at rest until acted on
by an unbalanced
force.
What do the ladder, driver, and
plates have in common?
INERTIA!!!
What is INERTIA?
Inertia: the resistance of an object to change
its motion
Inertia is determined by mass.
The larger the object is,
the more inertia it has,
so the harder it is to change its motion.
Why is it hard to change the
motion of a truck?
The truck is massive, so it has a lot of INERTIA.
Which has the most inertia?
Which has the most inertia?
What happens to Napoleon?
Napoleon is an object in motion and he remains
in motion until acted on by an unbalanced
force, because he has inertia.
YOUR TURN!!!!
• Get in a group of four.
• You will answer questions about Washers,
Test Crash Dummies, Pennies, and Racers.
• You must answer questions in complete
sentences, using what you learned about
Newton’s First Law and Inertia.
Washers
• Stack up 4 washers
• Flick another washer
at the bottom of the
pile
1. What happens when you
flick the washer at the
pile of four?
2. What does the stack of
washers have that keeps
it from moving?
3. Use Newton’s First Law
to explain what
happened. “The stack is
an object at ________.
It remains _________
because there is no
_________________.
Test Crash Dummies
4.
5.
6.
This test crash dummy remains
in motion until it meets the
unbalanced force of
______________.
When you are in a car and the
driver slows down suddenly,
what causes the unbalanced
force that stops your body?
(Assuming you are following
the law)
Your body keep moving even
when the car stops because your
body has _________________.
Pennies
• Stack a penny and a
card on top of a cup.
• Flick the card out.
7. What happens to the
penny when you flick
the card out?
8. Why doesn’t the penny
fly out with the card?
What does it have?
9. An unbalanced force
causes the motion of the
penny. What is the
unbalanced force?
Racers
•
10. Leave the car on your desk.
Why doesn’t it move? An
object at _______, remains
_______, until acted on by
______________.
11. Push the car on your desk.
The racer should remain in
motion until acted on by an
unbalanced force. What is
the unbalanced force that
slows down the car
Washers
• Stack up 4 washers
• Slide another washer
at the bottom of the
pile
1. What happens when
you slide the washer
at the pile of four?
The bottom one
slides out.
2. What does the stack
of washers have that
keeps it from
moving? Inertia
3. Use Newton’s First Law
to explain what
happened. “The stack
is an object at rest.
It remains at rest,
because there is no
unbalanced force.
Test Crash
Dummies
4. This test crash
dummy remains in
motion until it meets
the unbalanced force
from the air bag.
5. When you are in a
car and the driver
slows down
suddenly, what stops
your body? Seatbelt.
6. Your body keep
moving even when
the car stops because
your body has
inertia.
7. What happens to the
Pennies
penny when you flick the
card out? The penny
falls into the cup.
8. Why doesn’t the penny
fly out with the card? It
has inertia.
9. An unbalanced force
causes the motion of the
• Stack a penny and a
penny. What is the
card on top of a cup.
unbalanced force?
Gravity pulls the penny
• Flick the card out.
down.
Racers
•
10. Leave the racer on
your desk. Why
doesn’t it move? An
object at rest,
remains at rest, until
acted on by an
unbalanced force.
11. Push the racer on
your desk. What is
the unbalanced force
that slows down the
racer? Friction is
the force that slows
things down.