The Effect of Drag of a Note Card on the Speed of a Pinewood Derby Car down an Incline Plane

 

 

 

Kellen Comrie

 

  

 

 

 

 

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Table of Contents:

Introduction

Procedure and Design

Photos of Setup

Data Tables and Graphs

Conclusion and Evaluation

Physics I.A. text data .:. Excel

Related Websites

 

 

 

Introduction: The force of drag is often experienced in daily life, such as whenever you toss or throw anything, or how efficient or fast you can drive depending on the shape of your car. But it becomes paramount in the world of aviation, minimizing and accounting for drag in the creation of planes and rockets is very important. I wanted to visualize how much drag something creates on a object and I had a pinewood derby car from when I was 7 years old that could serve as a viable subject. My experiment uses force equations such as F=ma which finds the total force acting on an object(F) that accelerates and S=1/2at^2 which was what I used to find the acceleration of car(a).

 

Procedure and design:

 

Research Question: What is the Effect of Drag of a notecard on the Speed of a Pinewood Derby Car down an Incline plane?

 

Hypothesis: The larger the surface area of the notecard the more drag and the lower the speed

 

Variables: The independent variable is the size of the notecard with the length and angle of the plane and the pinewood car remaining constant the only dependent variable was the speed of the car

 

Materials:




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Photos of Setup:

 

Procedure: The best way to keep the times consistent was to balance the carís back wheel on the edge of the board. then release the wheel and start the timer at the same time. Wait for the back wheel to roll off of the board and end the timer. I would repeat this five times. Then place a cut to size notecard on the car and tape it in place. Repeat rolling and timing five times, then remove the notecard, cut it to size, and replace on car. Repeat until you have 5 sets of 5 data points. Move data to a google sheet and create a graph and used my calculator to find the acceleration in feet per second of the average velocity of a notecard using S=1/2at^2 where S= 4 ft, t= average time of the five points and solved for a. Then I converted the acceleration to meters per second and calculated the total force using F=ma  where m= 5 ounces, and a= the acceleration found earlier and got the force in newtons. I subtracted the force of a car with notecard for the force of the car without the notecard to find the force drag.




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Raw Data:

 

Area of NoteCard(cm^2)

Time(s)

0

1.91

2.04

1.94

2.03

1.93

40

2.16

2.09

2.06

2.1

2.05

50

2.16

2.05

2.23

2.13

2.05

60

2.19

2.13

2.09

2.26

1.99

70

2.24

2.18

2.13

2.19

2.26






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Table and Graph 1 represent time vs the surface area of the notecard

 

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Processed data:

 

Card size(cm^2)

Acceleration(ft/s/s)

0

2.0614

40

1.828

50

1.7733

60

1.76

70

1.6529

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Table 2 and graph 2 represent the acceleration of the pinewood car for each size of notecard

 

Acceleration in m/s/s

force in N

0.6283

84.08

0.5571

78.99

0.5405

76.63

0.5365

76.06

0.5038

71.43



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Table 3 and graph 3 represent the total force on the car as it traveled down the plane for each size of notecard.

 

Card size(cm^2)

Force of drag(N)

40

5.09

50

7.45

60

8.02

70

12.65

 

Table 4 represents the force of drag the notecard provided to the pinewood car

 

Conclusion:

The force of drag increased with the surface area of the notecard proving my hypothesis. This is supported by graphs 2 and 3 and table 4 with the highest drag belonging to the 70 cm^2 card. And the lowest acceleration also belonging to the 70 cm^2 card and the graphs trend lines are also down.

 

Evaluation: The raw data of this study is wildly inaccurate, By myself I would both time and release the car at the same time then listen to the back wheels to clack off of the board to end the time, There should have been another person releasing the car and I could have solely timed. creating inconsistent times. The board that the car rolls down is flat but has uneven smoothness adding another layer of uncertainty to this experiment. This experiment also neglects the acceleration of the wheels and friction of the board or air along with any effect the tape may have and on the drag as well.  The calculations of the force and acceleration was based off of a rounded average time for a notecard size. If I were to redo this experiment I would lengthen and sand the board down, have another person release and I would time (or better yet get a computer timing system). I would also have purpose built the car to this experiment, so that the use of tape would not have been needed. And I would run more trials for each card size along with using more card sizes.

 

Related Websites:

Nasa Parachute

††††††††††† Covers Traditional Drag forces but is focused on free fall while mine is based in incline planes.

University of Sydney sail force coefficients

††††††††††† Covers forces at level planes but is mostly focused on wind forces rather than drag.

Pinewood Derby wind resistance

††††††††††† Talks about wind resistance of car itself without a sail or notecard or parachute. Summary of next source.

Pinewood Derby wind resistance Video

††††††††††† Video that covers how the aerodynamic profile of a pinewood derby car changes the speed of the car.

Inspiration for Project

††††††††††† I saw this video years ago and liked the concept of adding harder science to these competitions and used the advice to do place well in said races.

 

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