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An object that is in motion will stay in
motion unless acted on by an unbalanced force. An
object that is not in motion will stay still unless acted on by an unbalanced force.
18 Wheeler - Video Demonstration
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| 18 Wheeler Jackknife - Inertia |
Explain why you think this happened:___________________________________________________________________________________________________________________________
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1.__________________________________________________
2.__________________________________________________
3__________________________________________________
4.__________________________________________________
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So What’s Inertia?
Inertia is the tendency* (what something wants to
do) for a moving object to stay in constant motion. Until an unbalanced force acts on the
object, it will keep moving at the same speed and in the same direction.
If
there was no air resistance or gravity, you could throw a ball up from the
top of a mountain and it would fly off into space. The ball would continue traveling in a straight line at the same speed until it hit a satellite or
planet. In reality, however, moving
objects change speed or change direction because they are acted on by
unbalanced forces. These opposing
forces can include friction, air resistance, and gravity.
Humans experience the Law of Inertia every time they drive in a
car. When the driver makes a quick
turn or stops suddenly, the passengers' bodies jolt and try to keep moving
in the direction the car was just going.
Because of inertia, it is very important that passengers in a car
wear their seat belts while driving.
Imagine this: You are
driving forward in a car at 40 miles per hour. The car is not just going 40
miles per hour – you are too! If the car suddenly stops, your body will
want to keep moving since it has inertia. In the case of an accident, seat
belts are a force that can keep a passenger from being thrown from the
vehicle.
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Lab #1: Crash Test Dummies
ÿ
Make observations about your toy
car.
ÿ
Do a “crash test” with your car.
Make the ramp as Mr. Miller instructs (with three textbooks) and drive the car
into the book.
ÿ
Add observations to your separate
sheet.
ÿ
Now make a “crash test dummy” out
of Play-Doh. This dummy should be about as large as a Lego man.
ÿ
Loosely place your dummy on the car and
repeat the crash test.
ÿ
Add observations to your separate
sheet
ÿ
Attach your dummy to your car as firmly
as you can. Repeat the crash test.
ÿ
Add observations to your separate
sheet and write your inference.
Lab 2: Mass and Inertia
ÿ
Make observations about the AAA battery,
including a mass.
ÿ
Copy the weight in grams in a complete sentence to your observation
sheet. (Ex: The battery weighs 15 grams.
ÿ
Ride the battery down a binder
ramp. With a meter stick, measure the distance that the battery traveled from
the ramp. If there is time, do up to three trials.
ÿ
Copy in a complete sentence the results of the three trials. (Ex:
In the three trials, the battery went 21 cm, 22 cm, and 18 cm.
ÿ
What other observations did you
make as it traveled?
ÿ
Make observations about the D
battery, including a mass. Copy the weight in grams to your observation sheet.
ÿ
Ride the battery down the same
ramp in the exact same way. The experiment must be fair! With a meter
stick, measure the distance that the battery traveled from the ramp. Copy in a
complete sentence the results of the three trials.
ÿ
What other observations did you
make as it traveled (velocity, movement, etc.) Add these to the sheet.
ÿ
Write your inference by using the
different trials as evidence.
Lab 1: Crash Test Dummy
Observations:
·
____________________________________________________________________________________
·
____________________________________________________________________________________
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____________________________________________________________________________________
Inference:
·
_______________________________________________________________________________________________________
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_______________________________________________________________________________________________________
Lab 2: Mass and Inertia
Observations
·
Weight of AAA battery in grams:
_________
·
Weight of D battery in grams:
_________
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Distance(s) AAA battery traveled:
_________________________________________________________________________________________________
·
Distance(s) D battery traveled:
_________________________________________________________________________________________________
·
Other observations:
_________________________________________________________________________________________________
Inferences:
·
_________________________________________________________________________________________________
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_________________________________________________________________________________________________
Above and Beyond
Do all objects have inertia? Why or why not?
Why do you think driving cars uses so much gas?
Why do you think you cars use more gas in the
city (stopping and starting a lot) than they do on the highway (going at the
same speed)? :)
Lifework
1) Inertia is the tendency of an object to
_____________________________ changing its _____________________.
2) Objects with more ______________________ have more
inertia.
3) Inertia is the reason that you need to wear a
______________________ in your car. If your car suddenly stops, your body will
want to keep __________________________.
4) Which of the following would have the MOST inertia?
a)
A marble
b)
A textbook
c)
A blue whale
d)
A car
Why?
__________________________________________________________________________________________
5) Give an example of inertia that you could observe when
you go roller skating.
_______________________________________________________________________________________________
6) Give an example of inertia that you could observe when
you ride a bike.
________________________________________________________________________________________________
7) True/False
All objects have inertia. __________
Objects only have inertia when they are moving.
__________
Newton’s first law is also called the law of inertia.
__________
Without an unbalanced force, an object that is not moving
will stay still forever. ___________
Friction is an example of an unbalanced force that stops
objects. __________
Mr. Miller generally has more inertia than his students.
__________
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