The Evel Knievel of ENG 2000 Final Report. Group 6

Transcription

1 The Evel Knievel of ENG 2000 Final Report Group 6 Name Gordon Klein Navjeet Singh Sarai Chris Kurulasuriya Mark Vincent Tee Student Number For Prof. Eshrat Arjomandi Engineering 2000 (Winter) April 6, Address frosty55@yorku.ca nsarai@yorku.ca cfern85@yorku.ca mvt@yorku.ca

2 Abstract The Evel Knievel of Eng 2000 project was a competitive project between six groups in York University s ENG2000 class. The purpose of the project was to design a vehicle which, without the aid of commercial batteries, can jump off a 15 degree incline and land on a target 5m away. The design had to be aerodynamic, aesthetically pleasing, had to travel exactly 5m, and had to cost in its entirety a total of $25 or less. The report discusses several different methods of propulsion that Group 6 considered, including explosion, compressed gas, elastic bands, and a number of designs that were banned from the competition. The design group 6 settled on was a rat trap augmented with elastic bands. A string was strung from a rod attached to the rat trap s arm, through a pulley to the drive wheels. The pulling force of the rat trap pushed the car forwards. This design was picked because it was believed that it had enough power to accomplish the project goals, and was a controllable, environmentally friendly form of energy. The report shows calculations which demonstrate that the car needed to accelerate to ~10m/s to launch the correct distance, and that a force of 5.0N applied over 2.0m was sufficient to accomplish that. Then it discusses the forces behind the car, and shows how the torque applied by the mouse trap is related to the applied force that pushes the rat trap forward. Experiments and testing showed that the car accelerated best when the rat trap was placed at the front, a 30cm rod was attached to the rat trap arm, and a small weight was applied to the front of the car. The best test results accelerated the car to 7m/s, which was still lower then the necessary amount of 10m/s. Our design remained approximately on budget, costing a total of $26.45 after taxes. The design went over-budget when some last minute changes had to be done just before demonstrations. The report discusses our project timeline, work breakdown structure, and AON logic diagram which describe our project management and schedule. We made fairly steady progress on our car, but only fully implemented one prototype which became our final design. The rat trap car design does not have any impacts on the environment since there are no emissions from the car while it is being used. Safety issues due to the snapping of the rat trap were discovered, and care had to be taken to ensure the safety of the group members. Demonstrations were held on the roof top of one of York s parking garages. The weather was sufficiently calm that it did not influence the results of the demonstration. The rat trap car failed to perform to specification. This was in part because the tires were slipping on the ramp, and also because the rat trap did not have enough power to propel the car with enough force. Design improvements like limiting the weight of the car and using multiple rat traps are discussed at the end of the report.

3 Table of Contents Introduction... 1 Background Information... 2 Vehicle Design... 4 Design Possibilities... 4 Explosive (Rocket) Powered Car... 4 Launcher Powered Car... 4 Glider... 5 Compressed Water Powered Car... 5 Elastic Band Powered Car... 5 Our Design... 6 Body Design... 6 Propulsion System... 8 Implementation Experimental Data and Testing Final Budget Details Work Breakdown Structure Project Timeline / Gantt Chart AON Logic Diagram Risk Analysis Environmental / Safety Issues Analysis of Demonstration References... 22

4 Introduction The Evel Knievel of Eng 2000 was an innovative, competitive project which combined both the presentation and engineering skills of the engineering students at York. The groups were assigned to make a car under an allotted budget of $25 which could launch off a ramp and hit a target 5 meters away from the ramp. There were six different groups participating in this project. A target called the green zone was supposed to be placed in the center of the target, with bonus points allotted to cars that can land in this green zone, but no cars hit the target, so the green zone was never used. Ramp specifications: Width: 40cm Length: 1.83m Incline: 15 degrees Target specifications: Distance from ramp: 5m Width: 1m Height: 1m The cars were allowed (and encouraged) to use alternative sources of power. The only power source that was not allowed was commercial electrical sources like batteries. Commercial products were allowed to be used, but entire car kits were not. The demonstration was an elimination style competition, where cars that hit the target advanced to the next round. Each round the target was placed 2m further away from the ramp. This implied that the car designs had to be capable not only of launching off the ramp, but launching in a controlled manner, so that the distance could be calibrated

5 Background Information A mouse trap racer is a vehicle that uses the potential energy that can be stored in a mouse trap to propel it forward. It is a design that many high-schools use as an experimental project in science classes. Many bright students have thought up clever ways of extracting every joule out of a standard mouse trap and propelling a car forward. It is a tried, tested and true technology. There are a number of variations on the typical mouse trap racer. There are elastic band powered cars, rubber band powered planes and boats, and balloon powered racers. One website that specializes in all of these hobby projects is a website called DocFizzix.com (see References section). This website sells plans, kits and specially machined parts for use in mouse trap cars and elastic band cars, but they only ship to the United States. Mouse trap cars are designed to travel in a straight line, and the aim of the game is either to get the greatest acceleration, or cruise for the longest distance. Since the design uses a mouse trap, weight is the number one most important aspect of the design. Mouse traps themselves hold little potential energy, so to get the greatest speed the mass must be as low as possible. Most of DocFizzix s designs are made out of balsa wood, and use a clever combination of gears and pulleys to extract as much power - 2 -

6 out of the mouse trap as possible. In most high-school classes, the typical choices for wheels are CDs, since they are cheap, extremely light, and easily accessible. However, CDs have almost no traction on the ground, which is a common problem in these designs. One feature that is common to almost all of the mouse trap designs on DocFizzix s website is that they all have an acceleration rod. This rod is attached to the mouse trap and changes the force/time ratio applied by the mouse trap. The trap transfers the same amount of potential energy in the end, but the rod causes the mouse trap to take a longer time to do it. The result is less force over a longer period of time, to give the car more time to accelerate to its maximum speed. The acceleration rod is the solution to the traction problems of the wheels. We decided to incorporate this into our design, anticipating that the rat trap would have issues releasing its potential energy too fast. Usually in mouse trap competitions the only project constraint is that you must use a single regulation mouse trap to power your vehicle. In this project, any kind of power source could be used, so while the mouse trap design was the basis for our project, we deviated from it and selected more powerful forms of propulsion than a mouse trap a rat trap. This will be discussed later in the report

7 Vehicle Design Design Possibilities There are several options that were considered as possible designs that could meet the project s constraints and goals. The following design concepts were considered while conducting our research: 1. Explosive powered car (possibly rocket propelled) 2. Car propelled by a launcher 3. Glider design 4. Compressed water 5. Elastic powered car 6. Mouse / Rat trap powered car Evaluating the available choices, certain designs were rejected due to constraint limitations and assumptions made by the team. Explosive (Rocket) Powered Car The explosive or rocket powered car was omitted early in the evaluation process. It was omitted because it was found to be too dangerous. Initially the information given to the group implied that the demonstrations were going to be conducted indoors. The fumes released by the rocket, as well as the general danger of a rocket powered projectile which could go out of control caused us to dismiss the idea of an explosive rocket propelled car. Launcher Powered Car The next idea was to have a launcher for the car and propel it across the ramp. A launcher has the benefit of having the car s power source be external from the car itself. There were many ideas that would allow the car not only to be launched the necessary distance, but also launched in a very measurable and calibrated way. However, a launcher violated one of the constraints of the project. The project specifications were revised early on in the project to forbid launcher powered cars. Since it was forbidden to have a launcher for the car this idea was dismissed in the early stages

8 Glider The glider design had very good advantages as it provided a way to allow the vehicle to make use of lift from the air as it flew. The car would need considerably less power to propel it off the ramp, which would have made it easier to get to the target from the initial launch. However, to accomplish a glider design, the design had to have wings. Similar to the launcher design, the project specification was revised to forbid wings on the car under the pretense that the car was supposed to be a land vehicle, and not an air vehicle. Since we were not allowed to have wings on the car the glider design was dismissed. Compressed Water Powered Car The compressed water car was a very possible option. The water was environmentally friendly, reusable, and the pressure could be calibrated for the right amount of power. However, just like the rocket powered car, we originally thought that the demonstrations were going to be performed indoors the compressed water car would make a mess of the area it was launched in. We also found that compressed water power cars were very difficult to control after the car has been launched. The car was very erratic when it was in the air, and it was difficult to land the car right side up. We eventually decided that the compressed water power car was not the best way to accomplish the project goals. Elastic Band Powered Car Next the elastic powered car was evaluated. We concluded that elastic power would not give enough power at all to get off the ramp, so once again this idea was also dismissed. The final choice that was left is the mousetrap or rat trap powered car. Our research which will be discussed later in this report showed that it was possible to use a mouse or rat trap to propel a car 5 meters in under one second. A rat trap was chosen over a mouse trap to provide more power. We decided on this design because we had seen examples of the design successfully built, and the designs we saw accelerated in a very controlled manner. Our final design and the building processes are discussed in the following section

9 Our Design Body Design Our vehicle is a modification of the typical mouse trap car, where the power of a mouse trap is harnessed to spin the front drive wheels and cause the car to accelerate. In our design, we replaced the mouse trap with a larger, more powerful rat trap. The arm of the rat trap is connected to a string, which is in turn connected to the drive wheels on the car. The pulling force of the rat trap applies torque to the wheels and accelerates the car. A more detailed view of how the forces work in the car is discussed in the Implementation section of the report. The following figure is a schematic of the design of the car from the top view; this has been changed from our previous design, both designs are shown in the following figure. 16cm 16cm 12cm 1" Bolt L-bracket with bolt L-bracket with bolt Rat trap 12cm 1" Bolt Rat trap 46cm 46cm Acceleration Rod / Arm Elastic constraint rod Spindle Hardboard Fibre base board base 30 o Fibre board siding Hardboard Fibre board base base 30 o Fibre board siding Acceleration Rod / Arm Added front weight Figure 1: Schematics of original design (shown on left) and new design (on the right). The base of the car is 46x16cms and made out of 1/8 hardboard. The rat trap was attached to the base using 1 bolts and nuts, spaced with a few centimeters of gap - 6 -

10 between the siding and the rat trap. This allowed the base to be very strong and ensures that the rat trap will not move in any direction even if a great amount of force is applied to it. The sidings were attached to the body using stainless steel L-brackets, fastened with nuts and bolts. This makes the sides adjustable, while still being securely attached to the car. The sides could be easily replaced if necessary. The side panels were oriented in such a way as to minimize air drag. The wings run in the same direction as the motion of the car, cutting through the air. The side panel is designed so that the incoming air to the front will cause as little drag as possible and the air that the flaps do interact with will be pushed off the top of the vehicle. In Figure 1 it is illustrated that there were several changes made to the original design. First the entire rat trap was moved towards the front of the car. The weight of the rat trap closer to the drive wheels helped reduce the slipping we experienced on the drive wheels, which is discussed in more detail in our Experimental Data and Testing section. The second change that was made was the elastic bands. Elastics were attached to the rat trap and tied to a rod mounted on the base, called the elastic constraint rod. The rod was made out of a bent coat-hanger, and supported all of the additional force applied by the elastic bands. A front weight was added to give the wheels added traction. The downward weight centered over the wheels would prevent the wheels from spinning out of control during the car s acceleration while the rat trap was closing. Finally a spindle was added to wrap the string around, in order to give the wheels more torque. The propulsion of the vehicle is discussed in the next section

11 Propulsion System The following figure illustrates the mechanical system which is used to accelerate the car forward. Figure 2: Mechanical system overview. A string is attached to a rod glued to the rat trap s arm. The string is threaded through a pulley at the back of the car, and fed through, under the mouse trap, to the front drive wheels and wrapped around the spindle attached to the front axle. As the string is wound, the rat trap and acceleration rod is pulled back, and the front wheels are wound backwards. This stores potential energy in the rat trap. When the car is released, the rat trap starts to close, applying tension force from the arm through the pulley onto the - 8 -

12 spindle. This force applies a torque to the front drive axles which accelerates the car forward. The motion of the axle spinning will be in the forwards direction as illustrated on the figure above. The pulley is an important part of the design, even though the force exerted from the arm would be perpendicular to the axles regardless of the direction of the force. The pulley allowed the acceleration arm to pull the longest distance of string through the spindle. If the puller were not in place, half of the motion of the acceleration arm would not result in pulling force, but instead in simply wrapping the string around the drive axle. The pulley allows the rat trap to be offset a greater distance from the spindle, which uses the rat trap more efficiently, and reduces the size of the body. The elastic bands that were added to provide additional power are shown in yellow. These elastic bands provided additional force along with the rat trap s spring assembly. The elastic bands were stretched only for the first half of the rat trap s motion, giving the car a quick starting acceleration, and a slower acceleration near the end. Our testing showed that this addition gave the car better acceleration and overall increased the final velocity of the car when it reached the top of the ramp. The revisions to our design improved the force and overall acceleration of the rat trap car

13 Implementation Our design requires the car to travel a minimum of 5m when it reaches the end of the ramp. Using projectile-motion calculations, we can determine the speed the car must be traveling to achieve this distance: (halflife) Vy = 0m/s v i v f 15 o d x = 5m A y = 9.8m/s/s A x = 0m/s/s F g Travelling time: v fy = v iy + at t = (v fy v iy) / a y v fy = 0 at the halflife of the projectile, so t = 2(-v iy) / a y total time of flight Distance traveled: d x = v ixt + 1/2a xt^2 No forces act horizontally on the car (ignoring air friction) a x = 0 so, d x = v ixt + 0 projectile motion Substituting t from earlier, d x = v ix * (2(-v iy) / a y) 5m = -2v ixv iy / a y 5m = -2vcos(15)vsin(15) / a y -5 / 2cos(15)sin(15) = v^2 / a y (-5a y) / 2cos(15)sin(15) = v^2 a y = -9.8 m/s^2 (-5*-9.8) / 2(0.25) = v^2 (-10*-9.8) = v^2 98m^2/s^2 = v^2 v = 9.89 m/s due to gravity

14 So as a rough measurement, our car must be traveling ~10m/s when it launches off the ramp. The following is a diagram of the forces present while the rat trap is activated T rat F t R arm Pulley R wheels T spindle F A R spindle F t T wheels T rat = Fixed constant. The rat trap delivers a fixed amount of torque. The difference in radius from the spindle to the wheels alters the amount of force the torque delivers to the car. F T = T rat / R arm T spindle = F T R spindle T spindle = T wheels because they are glued together. F A = Force applied due to torque on wheels (assuming the tires don t slip) = T wheels / R wheels Combining the above formulas: F A = F T R spindle / R wheels So it is clear that the torque supplied by the rat trap (causing a tension force on the string) can be converted into torque on the wheels, which is converted into a pulling force that moves the car. The pulling force is different from the tension force by a ratio of the radius of the spindle to the radius of the wheels. If this force is enough, however, is dependant on a number of other variables

15 An empirical measurement of our car in its best configuration shows that there is around 25cm of string that passes through the pulley from the beginning to the end of the rattrap arm s movement. This string is wrapped around the spindle on the drive axle, which is 1.5cm in diameter. We can use this information to determine how many rotations the drive axle will make. pi * d = c = 4.71cm 25cm / 4.71cm = 5.3 rotations circumference of drive axle And the wheels are approximately 12cm in diameter, so 5.3 rotations * pi * 0.12cm = 1.992m We can comfortably say that the car will accelerate for about 2.0m, at which point the rattrap will be closed and the car will glide, losing speed. How fast does the car have to constantly accelerate to reach 10m/s in 2.0m? (x - x o) = 2.0m v = vf = 10m/s v 0 = 0m/s (the car begins stopped) a =? Constant acceleration formula (5) 2 = (10^2 0^2) / 2a 2(2a) = 100 a = 100 / 4 = 25m/s/s The car must accelerate at 25m/s/s for 2.0m. F = ma = 0.300kg * 25m/s/s = 5.0N Using the same car setup as was described above; we came up with the following measurements for our car: Rwheels = 12cm = 0.06m Rspindle = 0.75cm = m Rarm = 30cm F T = 8N F A = F T R spindle / R wheels = 8N(0.0075m / 0.06m) = 1N The applied force was only 1/5 th the force needed to get the car up to speed. This explains why in our demonstration the car did not launch off the ramp, but only rolled up it and fell off the end

16 Experimental Data and Testing Test Parameters Qualitative Results Maximum Speed Wheels spun out 0.5 m/s Car did not travel in straight line Rod length: 8cm (min) Trap position: Back Full extension of trap Rod length: 12cm Trap position: Back Full extension of trap Rod length: 30cm (max) Trap position: Back Full extension of trap Rod length: 30cm (max) Trap position: Front Full extension of trap Rod length: 12cm Trap position: Front Full extension of trap Enhanced wheel grips Rod length: 30cm (max) Trap position: Front Full extension of trap Enhanced + cleaned wheel grips Elastic Band Augments Weighted Front Wheels spun in beginning. Traction for last 1/3 of trap motion Wheels gripped Didn t accelerate for first half of trap motion Wheels gripped for most of flight Full acceleration for entire motion of trap Wheels spun slightly in beginning Greater acceleration, but less period of time Mouse trap glided sooner Wheels did not slip at all. Car accelerated sharply at the beginning Glided for 1.5m before braking automatically Best test scenario 1 m/s 1 m/s 4 m/s 3 m/s 7 m/s Our initial testing showed that without the acceleration rod, at a distance of 8cm (the size of the rat trap kill arm itself) was completely insufficient. The wheels spun out completely, the car did not travel in a straight line, and the forward velocity it did reach was practically an accident. It was clear that there are a number of parameters that we could change, so in our testing we decided which configuration of those parameters gave the best results. All of our augments to the design were intended to either increase the traction, or increase the power of the car, since those were the two biggest problems we encountered during testing. We found that putting the rat trap at the front of the car helped improve the traction. We also found that putting strips of rubber on the wheels provided far better traction then our previous method of putting rubber bands around the wheels. When the strips were clean, it provided unparalleled traction far superior to the rubber bands. A 30cm acceleration rod (the maximum allowed by the design) also provided the best transfer of energy. Finally, adding weight to the front of the trap and augmenting the

17 mouse trap with elastic bands provided more power and better traction to the wheels., since our, resulting ultimately in our best test case. Our test cases, however, showed that even traveling in a straight line the mouse trap did not get up to the speeds we calculated that we would need. It is clear that on a ramp these speeds be even lower. While our testing showed that our design was successful in the scope of a traditional mouse trap race, it did not meet the criteria of this project. Final Budget Details $2.99 Rat Trap 2 x $0.99 Mouse Traps (Used only in earliest prototype) $1.99 Hardboard 2 x $0.79 L-Brackets 15 x $0.10 Nuts and Bolts 4 x $0.29 Wire grommets (Never used in design) $1.00 Kite string (1m long piece) $3.00 Zackz Wheels and Rubber Grips $2.00 Steel Axles / Acceleration arm (Found on side of road) $3.00 Lego Pulley $0.25 Teflon tape (15cm long piece) $1.00 Metal block for front weight (Borrowed from machine shop) $0.25 Piece of coat hanger 10 x $0.15 Elastic Bands Subtotal: $23.20 GST/PST: $ 3.25 Total: $26.45 Our final project cost was $1.45 over-budget as a result of taxes. However, some of the materials we bought, like the wire grommets, never got used in the design. Our project had to undergo some quick revisions just before demonstration day, adding elastic bands and anchoring them with a piece of a coat hanger, which also increased our expected cost

18 Work Breakdown Structure Evel Knievel of ENG2000 Project I. Design A. Researching for Potential Designs 1. Brainstorming 2. Advantages and Disadvantages B. Design Decision 1. Rat trap car II. Building Rat Trap Car III. Testing A. Materials 1. Hardboard, nuts, bolts, brackets 2. Rat trap, Acceleration rod, drive axle, string, pulley 3. Hand drill, saw, other tools B. Assembly 1. Cut the hardboard 2. Drill holes on rat trap and board 3. Assemble the main body together. 4. Attach acceleration rod to rat trap 5. Mount rat trap, pulley system, wheels and drive axle 6. Thread the car for actual testing A. Performing Test Runs 1. Flat Ground 2. CB 121 Angled Floor B. Analysis of Test Run Results 1. Insufficient force 2. Not enough traction C. Design Optimizations and Revisions 1.Addition of Elastic Bands 2. Addition of Weight in Front for Traction 3. Wheels Selection

19 Project Timeline / Gantt Chart

20 AON Logic Diagram

21 Risk Analysis We identified the following risk events during the entirety of our project: 1. Rat Trap The rat trap is capable of delivering enough force to seriously injure a person s finger. If one of our group members were injured, it would delay the project since somebody would have to take over the work they were doing. Severity: MEDIUM. Although the victim of the rat trap would be injured, this event would not seriously deter the project from moving forward. Another group member would take on the work the original member was doing. Likelihood: MEDIUM. Since we were constantly dealing with the rat trap s arm, sometimes more than one person at the same time, the risk was always present. Response: Accept/Reduce. The rat trap is the heart and soul of the car, and we could not do without it, and the use of PPE would be too cumbersome and inhibit project development. Care was simply taken in handling the rat trap, and all group members were informed of the risks. No one was hurt from the rat trap. 2. Machinery Safety and Equipment for constructing the car, we needed to use saws, drills and other power tools; and if not properly used, there is a risk of injury to the team members. Severity: HIGH. Saws, drills and power tools could easily cause permanent, even life threatening injury if not used properly. It was also possible to damage our building materials with improper drilling/cutting, which could result in the project going over budget. Likelihood: LOW. Using the safety equipment provided with the tools, and with common sense, this risk is reasonably low. The risk was gone after construction of the large parts of the car was finished. Response: Transfer/Reduce. The most dangerous cutting will be performed by the student machine shop assistant on duty at York and we made sure we used proper personal protective equipment like gloves and goggles whenever we used the saw and drill. 3. Material Damage there is always the risk of breaking or ruining some of the parts in our project, during testing, or as a result of an oversight by one of our group members, material could be damaged which would cause the project to go over budget, and delay it while new materials were being purchased. Severity: HIGH. Breaking of a critical or expensive component like the wheels or the body at the time of testing would set the project back tremendously Likelihood: MEDIUM. An oversight by one of the group members, or a failure during testing was always possible throughout the lifetime of the project. Response: Reduce: We ensured we had spare material on hand in case they failed unexpectedly, and designed our car so that components could be swapped out

22 Environmental / Safety Issues Since our car is not powered by any chemical means, and does not emit any gases or liquids, there are no environmental concerns related to our design. There are a number of safety issues related to this project. Saws, drills and other power tools needed to be used to assemble the car, and proper personal protective equipment had to be used. In one case, a saw broke in half while it was being used. Pieces of metal had to be cut using jigsaw, which caused shards of metal to fly in all directions. Nobody was hurt during construction, but without gloves and goggles there may have been a greater risk. The rat trap itself posed a hazard as well. When fully wound back, the rat trap had enough power that if it were to slip and snap shut, it can break fingers. Special care had to be taken to ensure that nobody ever had their fingers in the path of the rat trap while it was engaged. The frame itself also had sharp corners, which can be dangerous when the car is moving at fast speeds (and being caught by the catcher at the end of the test run). We rounded the corners of the car to make it safer to catch for the final test run. Analysis of Demonstration The ramp was made out of plywood, and smoothed at the bottom using a piece of aluminum sheet metal. The demonstration was done on the roof of one of the school s parking lots. There were minor winds, but no precipitation. It was cool, but above zero degrees Celsius outside. All of these factors we believe did not have an affect on the overall outcome of the demonstration

23 Trial 1 The car s wheels spun at the bottom of the ramp and the car traveled approximately halfway up the ramp. It did not make it to the top of the ramp, and did not reach the 5m target. We believe that the car did not have proper traction on this run. The ramp had dust and debris on it, which we believe compromised the traction on the wheels and stopped them from gripping the ramp. Trial 2 The second trail was more successful than the first. We started the car on the ramp itself, instead of on the sheet metal. The rat car s wheels still slipped, but they gripped better than the first trial and the car made it off the ramp. The car, however, simply fell off the end of the ramp without traveling any recordable distance. The car did not reach the 5m target. Conclusions Even though the wheels did not have complete grip on the ramp, it is clear that the rat trap car would not have flown 5m to its destination target. The trap, even when augmented with elastic bands, simply did not have enough power to propel the car off the

24 ramp with the speed needed to reach the target. Overall, the demonstration was not a success. There are a number of changes to our design which may help to improve the car s performance. The car s materials should have been lighter. Our original assumptions implied that the car would weigh less than 300 grams, but our car weighed in at as much as 700 grams. The main concern originally was that the car would break when it hit the ground, so strong parts were used as the materials for the car, but in hindsight, car could have used much lighter and weaker materials and still survived. The rat trap itself could have been replaced with a dual rat trap system, where two or more traps were used at the same time to provide more power to the car. A dual system was considered in the early stages of the project, but eventually dismissed due to its complexity, but in hindsight it may have been a better option to explore then augmenting the rat trap with elastic bands. Finally, it is clear that a major problem with the design was traction on the wheels. It is conceivable that using different treads or differently shaped wheels might have given the car better traction on the ramp. However, it seems apparent that the entire design of using a set of drive wheels to propel the car may not be a realizable idea at all. The drive wheels simply do not get enough traction on the ground (especially when the car s weight is minimized) to propel it with the force needed to accelerate it up to 10 m/s. Perhaps a different design that incorporated a much longer approach would have been more successful, but an approach that was shorter than the ramp itself was clearly insufficient. While the design succeeded in doing what it was designed to do, it did not accomplish the goals of the project. More revisions are needed to the design to have it accomplish the project goals

25 References DocFizzix Mousetrap Cars, Boats and Racers Photographs of Mousetrap Cars from Billings Senior High, MT. USA Halliday, Resnick, Walker, Fundamentals of Physics (7 th Edition). USA: John Wiley and Sons, 2005 Constant Acceleration Forumlas: Projectile Motion Simulator (to test the calculations): Torque Wikipedia