Research Q and A`s

Hey, DV! 


Before building the base of our Mouse Trap Car, we have some questions to answer. 
These answers will help in the understanding of what works and what doesn't when building
a Mouse Trap Car.


1. What are the two types of friction that affect the performance of your vehicle and why?
        There are two types of friction, surface friction and fluid friction. Surface friction is caused by the rubbing of two surfaces in contact with on another. Where your axle connects to the frame of your vehicle is one place that you will find surface friction on your car. By reducing the surface friction with graphite powered or ball bearings you will see an increased performance with your vehicle. Traction is a wanted surface friction that is between your vehicles wheels and the flooring, increasing your tracking will allow for greater accelerations because it will take more torque to make the wheels spin out or break loose. Fluid friction is caused by an object trying to move the air out of the way. Make your car aerodynamic so that it is easier to push the air aside.  --http://www.docfizzix.com/


2. What problems related to friction did you encounter and how did you solve them?
       Before using vinyl records for wheels, we noticed that the surface friction between the chloroplast wheels and the ground were causing the mousetrap car to slow down to a stop. That is why we chose to buy vinyl records, there is less contact between the floor and our wheels, therefore less friction. 
       Also, we tried testing our mousetrap car on a carpeted floor and it moved only a bit. The carpet had created so much friction that it trumped the potential energy stores in our mousetrap. Tip: Do not preform your test drive on carpet or any other non-smooth-sleek -surface.


3. What factors did you take into account when deciding the number and type of wheels you chose in your design?
       We orignially had a problem deciding whether to use three or four wheels, but decided on four wheels for balance. Other than that, we do not believe there is a difference in using 3 or 4 wheels! What matters is having the largest diameter for your back wheels. The bigger they are, the more ground you cover in one revolution!
      Choosing the type of material you want to use for your wheels is very important!
Remember that you are not looking for a racecar, but a long distance car. Chloroplast is great, but what`s better are records and CD`s. They have manufactured, round edges; unlike chloroplast which you would have create and sand.


4. How does Newton's first, second and third  laws apply to the performance of your vehicle?
Law 1: The velocity of a body will remain constant if no external force is applied:
Accelerate the car to 50 km/h, and keep the speed constant. Now the amount of force the motor applies to the car for forward movement is the same as the resistance force (resistance force = air resistance + roll resistance). In other words, there is no net force, the velocity remains the same. If you release the gas pedal, the force of the resistance is bigger than that of the motor and the car will slow down.

Law 2:The acceleration of a body is parallel to the net force F according to F=ma.
Again, the car accelerates, the force applied by the motor is bigger than the resistance force , the car accelerates forwards.

Law 3: An action on a body requires an opposite, but equal in strength, reaction. 
When the car collides with another car, both cars experience the same force. Say the second car is standing still and your car is moving: the force with which your car stops will be the acceleration of the other car.
Source:http://answers.yahoo.com/question/index?qid=20111102200121AA13x1k

5. What are the effects of the length of the lever arm in the pulling force of your vehicle?
        The longer the lever arm is; the farther it will go.


6. How is the balance of a wheel related to the vehicle’s performance?
        If your wheels are not straight, they will roll sideways and that will cost you distance. 
A straight line is longer than a diagonal one.
Tip: Try triangulation on all sides of your wheels.


7. How can we calculate the average speed of our car?
        Using a distance versus time graph. See here for more details : http://graphs.mathwarehouse.com/distance-vs-time-graph-lesson.php


8. How could increasing the diameter of your wheel affect your mouse trap car? 
        The  bigger your diameter is, the better. Bigger wheels cover more ground in one revolution, therefore a longer, overall distance travelled.


9.  Where is the potential energy stored in your mouse trap car?
        In the mousetrap attached to your mousetrap car.


10. How do mousetrap cars designed for distance differ from those designed for speed?
        A good distance car will not be a good speed-trap car and so on. When you build a mouse-trap car for distance, you want a small energy consumption per second or a small power usage. Smaller power outputs will produce less wasted energy and have greater efficiency. When you build a vehicle for speed, you want to use your energy quickly or at a high power output. You can change the power ratio of your vehicle by changing one or all of the following: where the string attaches to the mouse-trap's lever arm, the drive wheel diameter, or the drive axle diameter. The amount of energy released by using a short lever arm or a long lever arm is the same, but the length of the lever arm will determine the rate at which the energy is released and this is called the power output. Long lever arms decrease the pulling force and power output but increase the pulling distance. Short lever arms increase the pulling force and the power output by decrease the pulling distance but increasing the speed.

Source:http://www.docfizzix.com/mousetrap-car.shtml