Mouse Trap Car

Like we said in the previous blog, there are numerous ways to create and build your mouse trap car. Depending on the requirements of your designs, you can modify or include additional parts in your vehicle that could improve its performance. We will list down the possible modifications the you could include in your mousetrap car but remember not to limit your modifications and enhancements to the listed suggestions. Be creative and explore other possibilities. These are just examples which we hope would jump start your ideas in building your mouse trap cars.

Photo Courtesy Of FunTraps

• Extension of the lever arm – what you could do here is extend the lever arm of the mouse trap by attaching a rod on the mousetrap’s jaw. You can secure it with a wire or string or duct tape. At the end of the extension, tie the string that is meant to rotate the drive axle.

By extending the lever arm, the force required to turn the drive axle decreases. By doing so, the stored mechanical energy in the snapper’s lever is conserved while constantly turning rotating the drive axle. This adjustment would guarantee your car to travel longer distances because no energy is wasted in moving the vehicle. The downside with this option is that the speed of the vehicle will be compromised. This vehicle will travel great lengths but at an obviously slow pace.

Inversely, if the lever arm is short, the speed of the mousetrap car would be faster as compared to an extended lever arm. Remember that a shorter lever arm will require a greater amount of force and speed is relative to the amount of force applied.

To illustrate this idea, imagine a ball tied to a string. If you spin the ball around you while you hold on to the other end of the string, you will see the change of speed of the revolving ball as the length of the string changes. Assuming that all factors are constant, a shorter string will cause the ball to revolve faster as compared to a longer string. At the same time, for the ball to complete one revolution, the ball will have to travel farther if the string is longer as compared to when the string is shorter.

• Increasing the drive wheel’s diameter – A drive wheel with a bigger drive wheel will result to traveling farther assuming no other parts will be adjusted.

  If you increase the diameter of your mousetrap car’s drive wheel, then it will travel great distances. The reason for this is that a wheel with a bigger diameter will cover a longer distance before it could make a complete turn. But there is a downside to this : your vehicle will travel slower.

  A bigger tire will require more force for it start moving from rest, more power to accelerate but at the same time it will also more force for it to stop as compared to a smaller one. This is because wheels are subject to rotational inertia. Another characteristic or rotational inertia that a designer must consider is the displacement of energy in relation to the distance of the rotational axis to the bulk of the mass. If the distance of the bulk of the mass from the axis is greater, then the amount of energy required to move it is also greater.

  Inversely, a smaller drive wheel diameter will produce greater speeds. This is because smaller wheels will require a smaller amount of force to displace around the mass of the tire for it to move. But then, it will only travel a short distance because the mass is smaller therefore only a small amount of external force is required to affect its rotational inertia.

  To illustrate this theory, imagine the ball and string again. Pretend that it’s path is the path of the rotational inertia. If you start with the ball at rest, it would be significantly easier to start moving the ball with a shorter string as compared with a longer string.

• Increasing the diameter of the drive axle – you can increase the diameter of the drive axle either by using a thicker rod or by adding tape around the original axle. This will increase the speed out put of your mousetrap car.

  By increasing the diameter of the drive axle, assuming the the size of the drive wheel doesn’t change, will variably increase the speed of the contraption.

  The increase in the axle’s diameter will increase the torque applied by the same amount of force. In effect, you will increase the power used to turn the wheel and since you will increase the power used to turn the wheel, and since speed is correlated to power, this adjustment will generate higher speed.

• Reducing the mouse trap car’s weight – this will require, either the use of lighter materials or the removal of parts that are not needed and are simply dead weight.

  By reducing the weight of the car, you are efficiently converting the potential energy of the snapper’s spring into kinetic energy. A lighter vehicle will have less inertia and therefore will require less force to accelerate it. This also implies that since it will only require less force to accelerate it, the time required for the vehicle to reach its maximum speed will also be shorter. Thus, the mousetrap car will be a faster vehicle as compared to a heavier car.

  Meanwhile, a heavier design, assuming the wheel to axle ratio remains the same, will ultimately result in a coverage of a longer distance. As the third law of inertia states, a moving object with greater mass will require a larger amount of external force to stop it from moving as compared to a moving body with a smaller mass.

  To illustrate this, imagine catching two falling objects. It would be far easier to break the fall of a pillow dropped from the second floor of a building as compared to a piano dropped from the same height.

• Using thinner and lighter drive wheels – instead of using thicker tires for your mouse trap car, use thinner and lighter tires like, plastic plates or CD’s or DVD layers. This will increase the maximum distance that your vehicle could travel and the increase the acceleration of the vehicle.

  A lighter set of wheels will mean that the rotational inertia of that particular part is also less. One might think that this negates the previous suggestion by increasing the car’s mass. That may be the case but there’s a good explanation for this.

  You can apply the newton’s third law of inertia on the wheels if you’re only objective is to make the wheel travel a great distance. But what we are trying to do is to move the whole mousetrap car forward. This means that apart from the energy required to accelerate the drive wheels, an additional amount of energy is required to displace the whole car.

  The problem is that there is only a limited amount of potential energy stored in the mouse trap’s spring. And when this energy is transformed from one form to another, the energy is consumed. So if more energy is alloted to the rotational inertia, then the efficiency of energy use might be compromised.

  By using a thinner and less massive drive wheel, less energy is displaced for the rotational inertia and more energy is displaced in the forward movement of the whole mousetrap car. With this adjustment, the distance car would travel could be enhanced significantly.

  At the same time, since less amount of pulling force is applied to the rotational inertia, more energy is then utilized to achieve the maximum speed of the car.

• Reduce friction – What you can do here is apply graphite powder or lubricant to the moving parts of your vehicle, in particular, the axle, and the washers.

  Friction is another type of force that is acting on your car. More importantly, the moving parts of your mousetrap car. This will affect both the speed and distance output. If friction is allowed to act on the vehicle, the kinetic energy that moves the car will be turned into heat energy because of the chemical reaction between that is taking place between the contacting surfaces.

  This transformation of energy to heat will consume the energy that could be used for the desired motion of the vehicle. This means that if friction is not reduced, then the supposed speed or distance that the car could achieve will be sacrificed in exchange for heat.

• Increased traction - If you are using wheels with a smooth surface, it is wise to add rubber for traction. One popular method is to add a portion of a balloon to the circumference of the wheel.

  Increased traction will require an increase in surface are that will be subject to static friction. Static friction is different from the friction mentioned above. The one mentioned above is kinetic or sliding friction, the force that affects two moving bodies in contact. Static friction, on the other hand is the type of force that prevents two bodies to slide when in contact.

  This means that the rotational force coming from the spinning drive wheel requires traction so that it would be able to apply a pushing force on the ground to make the vehicle move forward. Without traction, the wheels of the car would slip and cause an energy expenditure without any work output. With an increased traction, the grip of the tires on the ground will be more stable resulting in a higher speed.

  This adjustment is not advisable to long distance cars. Smoother wheels for mousetrap cars will result in longer distance traveled.

These are just some of the adjustments that you could apply in your mousetrap car. Of course, the possibilities are not limited to these suggestions. Remember that when planning your design, you should practice your creativity, your imagination and your cognitive thinking. Try to mix and match all the Physics theories that you are aware of and apply that to your mouse trap car.If you have knowledge on using gears and pulleys or if you know about aerodynamics, then go ahead and apply it. Below are images of mouse trap cars with modified parts.

Photo Courtesy Of http://www.docfizzix.com

Click On the Images to See Enlarged Photo

Do not limit the improvements of your car to single adjustments. You can apply more than one of these suggestions to your car as long as there is enough torque to start moving your car. It would be good to find the best combinations of adjustments to produce an efficient and high performance mousetrap car. All you have to do is find the optimum combination among these suggestions.

So start planning your mouse trap car design and hopefully, these suggestions could help you come up with either a fast or a long distance mouse trap car. Be creative with your designs but never forget to be realistic.