Motion+Project+Questions

Motion Project Questions

Reminder: The guidelines and notes for this project that were discussed in class are posted on the Physical Science wiki page on the date that we first discussed it. I had a number of questions and the answers to them typed up, but my device went dead without them being saved, so I will need to retype them. I will do so as soon as I can. They will show up here - stand by!

A) The car must ROLL along the floor for 10 m (and cross the finish line through a 3 m span. The car must have 4 wheels - two each on a front axle and a back axle - like a typical car.
 * Q#1. Can the car have stabilizers on it? (After clarification, the "stabilizers" apparently meant some sort of wings.)**

A) NO. Again, it must roll.
 * Q#2. Can the car skid or slide on the floor.**

A) No. See answer #1.
 * Q#3. Can the wheels all be in row?**

A) First of all, a launcher is not required. It depends on the design of the car. Many cars can be built that can move without a launcher. No restrictions have been placed on the size of the car or the launcher, BUT be aware that there is 3 to 4 ft of room between the starting line and the cabinets. I have not put any restrictions on the size of car either, EXCEPT for being limited by the space between the starting line and cabinets as mentioned earlier.
 * Q#4. How big can the launcher be?**

A) Neither the size nor the number of rubber bands has been spent specified. Remember two things however, they must be used only as power source and not as a structural material beyond that, and they must be rubber bands. Elastic, workout/exercise bands, small inner tubes, etc are not acceptable. . A) First of all, make sure you have reduced friction as much as possible. Check key things like: 1) The point where the weight bears down on the axle attachments - a lot of surface contact will give more places to add friction 2) Are the wheels rubbing against the body? 3) Are the wheels smooth and round? Bumpy, irregular wheels will rob motion from your car. Also, larger wheels tend to roll more smoothly since irregularities in the roundness of the wheel will not be as noticeable with a larger circumference. Secondly, we discussed using torque (pronounced "tork") to your advantage. Torque is rotational leverage. Using a longer lever to move an object give you more advantage. The fatter your axle is, the farther from the center of the axle the rubber band is from the center of the axle and that gives your car more torque and enhances the force from your rubber band. This may help to overcome the inertia from rest and get it moving. Once the car is moving (already in motion), it is generally easier to keep it moving so the rubber band could wind down onto a narrower axle and still keep the cat moving. In fact, the smaller the axle, the more winds you will get off the rubber band and that produces distance rather than extra force.
 * Q#5. How many rubber bands can I use?**
 * Q#6. When I add weight, it does not go as far. What can I do about that?**

A) No. If you build a launcher, it will need to be self-supporting and not attached to floor, EXCEPT for the fact that you can hold the launcher down by hand or foot to keep it from sliding backward while you pull the car back.
 * Q#7. Can I tape my launcher to the floor?**

A) Yes. You can use any size or number of rubber bands you want, BUT remember that the rubber bands are used ONLY as the power source, not as a structural building material
 * Q#8. Can I link rubber bands together?**

(These questions were lumped together because the answers are related.) A) The intent was for the car to go as straight as possible and that was alluded to in class from the beginning. There will be some flexibility on this as the starting line will be 2 ft wide and you will be allowed to position your car where and how you want within that 2 ft. However, the alley we use to run the cars will only be a certain with, so the more you car's path bends, the higher risk you are taking that it will hit the side of the course and not make it 10 m.
 * Q#9. Can I aim my car how I want, or does it have to go down the middle the whole way? How much room will we have for the car to curve? What if my car curves significantly in one direction... will the course be wide enough for the car's path to bend way out and come back in through the 3 m span at the finish line?**

(More later)