Transcript 114573_Sail_Car.pptx

Sail Car
SDQ
1. You know a sailboat can go down
wind, how does this work? (think of a
kite)
2. Can sailboats really go up wind? If
so, how do they manage this?
DSQ

A researcher is curious to find out what effect
classical music has on people’s level of relaxation
(as measured by heart rate). He suspects that
listening to classical music will make people feel
more calm and relaxed. He lets one group listen
to classical music for one hour. He lets another
group sit in a quiet room for one hour (i.e they
hear no music). After one hour, he monitors the
heart rate of each participant to measure their
level of relaxation.
1. What is the independent variable?
2. What is the dependent variable?
Make Booklet
 Please
fold __ sheets of paper
together.
 On the front page
Title:
Sail Car
Name
Date
Page 1: Objective
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Build base of car and study speed and friction
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Build a wind power car that will travel the fastest
over a distance of 15 ft downwind.
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Modify car to travel upwind over 10 ft.
 Side
objectives
 History
of sailing
 How to calculate speed
Page 2: Materials
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cardboard
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straws
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dowel rod
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Bbq skewers
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white paper
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Plastic garbage bags
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Paperclips
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Tape
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Approved additional materials
Car Base
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Cut cardboard rectangle –
6 -8 inches x 10-14 inches
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Wheels (4 wheels recommended. You can try 3 but it’s tricky).
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Bottle caps
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Axle
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Size matters, you need to pick
Type of axle
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Wood dowel
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Coffee straw
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Bbq skewer
Things to consider before building.
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Friction
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Ballast
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Mass
Static Friction
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Four types of friction are shown in Figure 6. The
friction that acts on objects that are not moving is
called static friction.
Because of static friction, you must use extra force
to start the motion of stationary objects.
For example, think about what happens when you
try to push a heavy desk across a floor.
If you push on the desk with a force less than the
force of static friction between the desk and the
floor, the desk will not move.
To make the desk move, you must exert a force
greater than the force of static friction.
Once the desk is moving, there is no longer any
static friction.
However, there is another type of friction—sliding
friction.
Sliding Friction
Sliding friction occurs when two solid
surfaces slide over each other.
 Sliding friction can be useful.
 For example, you can spread sand on an
icy path to improve your footing.
 Ballet dancers apply a sticky powder to the
soles of their ballet slippers so they won’t slip
on the dance floor.
 And when you stop a bicycle with hand
brakes, rubber pads slide against the tire
surfaces, causing the wheels to slow and
eventually stop.
 On the other hand, sliding friction is a
problem if you fall off your bike and skin your
knee!

Rolling Friction
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When an object rolls across a surface, rolling friction occurs.
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Rolling friction is easier to overcome than sliding friction for
similar materials.
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This type of friction is important to engineers who design
certain products.
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For example, skates, skateboards, and bicycles need wheels
that move freely.

So engineers use ball bearings to reduce the friction between the
wheels and the rest of the product.

These ball bearings are small, smooth steel balls that reduce friction
by rolling between moving parts.
Fluid Friction
 Fluids,
such as water, oil, or air, are
materials that flow easily.
 Fluid friction occurs when a solid
object moves through a fluid.
 Like rolling friction, fluid friction is easier
to overcome than sliding friction.
 This
is why the parts of machines that
must slide over each other are often
bathed in oil.
 In this way, the solid parts move
through the fluid instead of sliding
against each other.
 When you ride a bike, fluid friction
occurs between you and the air.
 Cyclists often wear streamlined
helmets and specially designed
clothing to reduce fluid friction.
Speed notes
Down Wind Notes
Upwind Notes
Page 3-4: Terminology
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Please see sail car online activity
Page 5: Point of Sail & Lift
Page 6: Speed
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Speed: distance traveled divided by the time taken.
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S = d/t
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Per = divide = /
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Common distances: inch, foot, mile, centimeter, meter
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Common times: second, minute, hour, day
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Common speeds: f/s, mi/min, mph, c/min, meter/sec
Page 6: Speed Continued
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Practice Problem
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1. You dive 200 miles in 5 hours. How fast were you driving?
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2. You walk 30 feet in 5 seconds. What was your average speed?
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3. You drive to Girdwood to go skiing. Girdwood is 35 miles away. It
takes you 45 minutes to get there. What was your average speed in
miles per hour.
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Challenge 4. You are driving to Homer, AK this weekend. Homer is
218 miles away. You are driving 55 mph. How long will it take you?
Page 7: Downwind Design
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In the top of your page:
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Please write down some ideas that you have for your design. (think
about axles, your sail, attachments)
In the bottom half (majority) of your page:
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Please draw your design.
Page 8: Downwind Conclusion

Please look at the class results and write a response.
What do you think about your design. How did it
preform. How did it preform compared to your
classmates. Please include the speed of your sail car.
What would you do different next time. Please include
4 vocabulary words or words you learned during this
unit. Please underline these words.
Page 9: Design Upwind

In the top of your page:


Please write down some ideas that you have for your design. (think
about axles, your sail, attachments)
In the bottom half (majority) of your page:

Please draw your design.
Page 10: Upwind Conclusion

Please look at the class results and write a response.
What do you think about your design. How did it
preform. How did it preform compared to your
classmates. Please include the speed of your sailcar.
What would you do different next time. Please include
4 vocabulary words or words you learned during this
unit. Please underline these words.