Transcript Homemade Crash Barrier Experiment Question

Agenda
• 1. Into to Newton’s Laws
• 2. Using Newton’s Laws to build a smart
barrier
• 3. Experiment
• 4. Final Conclusions
An object in
motion
stays in
motion and
an object at
rest stays at
rest unless
acted upon
by an
outside
force
• For every action there is an equal and
opposite reaction
I need ya’ll to come up with one reason for each
law why a person would be injured during this
crash…..
Newton’s First Law :
Fly through the windshield because a person keeps going unless
acted upon by an outside force (concrete wall, windshield, tree,
seatbelt or airbag)
Newton’s Second Law:
The force exerted on a car depends on the mass and acceleration involved…
the massive deceleration of a crash unleashes a huge amount of force on the
wall or other object that is hit……….
Newton’s Third Law :
…. The force exerted by the car on the wall= the force exerted by the wall back on
the car… we can calculate this using the video
1.Car was moving with a velocity of 70 mph(30.8 meters per second)
2.Car went from 30.8 m/s to zero in .016 seconds (average impact time for
smart car)
3. Acceleration= Final Velocity-Initial Velocity =
Time
0-30.8 = -1925 m/s/s
.016 S
4. Force= Mass x Acceleration= 730 kg(smart car mass) x 1925 m/s/s
1,405,250 newtons of force exerted on the car. If I stood on your head I
would exert about 700 newtons of force. Imagine 2000 times more force!
• What are two ways we can decrease the
force on a car?
1. Decrease Mass of the Car
2. Decrease acceleration on impact…. How do we do this?
Acceleration= Vf-Vi
t
INCREASE
STOPPING TIME!
If we keep velocity the same what
could we change to diminish
deceleration………
• Name two things in your car that slows
you down during a car crash?
1. Seat Belts
2. Airbags
Airbags act like an air baggy barrier, their thickness slows down your
head as it flies forward and it also prevents a collision with the
steering wheel
• Today you are going to perform an
experiment to see if a barrier that you
build yourself can slow down a car
enough to decrease impact force.
Homemade Crash Barrier
Experiment
Question: What will happen to the
force on a car when it collides with
a concrete wall if a homemade
barrier is placed in between the car
and wall?
Hypothesis(will the force increase
or decrease):
Materials
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1. one friction car
2. kg weights for mass
3. sturdy clay, about a half a cup or one stick
4. 10 straws
5. 1 meter of masking tape
6. 10 cotton balls
7. 10 Popsicle sticks
8. 10 x 10 cm square of aluminum foil
9. At least a 30 cm ramp
10. concrete block
11. 3-4 cm ruler with mm visible
12. electronic balance
13. one half popsicle stick
Method
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1. First of all you need to figure out how
much force is exerted on the friction car
when you crash it into the wall without a
barrier.
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Run five trials with this setup:
Method
A.
B.
C.
D.
E.
F.
G.
H.
I.
J.
Find end of friction car with longest edge from wheel.
Make one tube of clay into a square and place it on edge of friction car so
that a centimeter or two is hanging over
Place half popsicle stick into clay so it is sturdy, mark point where clay
and stick overlap with pencil
I advise you add mass to car. Now use electronic balance to find the
entire mass of the system, write this in your data table
Place ramp on half concrete block
Bottom of ramp should be at least 25 cm from brick collision wall
Place car with its back wheels at the top of the ramp and release
The popsicle stick will collide first with wall and should penetrate the clay
even more. Mark again where the sick and clay overlap.
Take stick out and measure the displacement of the stick…use a miniruler to find the displacement in millimeters. Place this in your data table
under trial 1.
Repeat four times and then average.
Building Method
• You will now build a barrier out of the
limited supplies given to you.
• You will test if the barrier decreases the
displacement of the stick
• Run five trials with your barrier and
average
• Write your interpretation of the data
• Answer the conclusion questions the best
you can