[*boongee]

Hi everyone<3

im new to Science forums, people told me that this was the best place to go to if i needed help with my project.. so im here =)

well, im in grade 11 and our PHYSICS teacher just assigned us a project where we have to construct a rubber band car.

If it was just the car.. it wouldn't be as hard, but we have to utilize 2 rubber bands that must go 5 meters within 30secs and cannot weight more than 2.0kg. Also 3 meters through, it must drop a coin on a 'X', and how close we are to the 'X' will determine our mark.

I've researched enough to understand how to construct a car powered by one rubber band, but i have no clue how im going to incorporate the coin, AND the other rubber band...

can anyone help me? =) thank you in advance you super duppper smart people =D

[Cap'n Refsmmat]

Could you outline your current plan for us?

[CraigD]

*boongee said:

I've researched enough to understand how to construct a car powered by one rubber band, but i have no clue how im going to incorporate the coin, AND the other rubber band.

I think you’ll find that a design using one rubber band will require just a little change to use 2. 2 rubber bands together are much like a single, stronger rubber band.

Consider that there are 2 obvious ways to store energy using rubber bands:

• twisting, as in a wind-up toy airplane
  
• stretching, as in a sling-shot

A simple way to turn wheels with stretched rubber bands is to wind a sturdy thread around an axle connected to 2 wheels, and connect that string to the bands. How quickly the car accelerates, and how far it goes, can be adjusted by changing the diameter of the “spool” part of the axle where the string is wound, and/or the diameter of the wheels.

A simple way for a precise coin-dropper is to push the coin is to have something push the coin toward the edge of a “shelf” so that it falls off at a given distance. Although many designs are possible, if the car has an axle that is turned by stretched rubber bands, the same parts used for the rubber bands can be used to push the coin.

I expect the rubber bands you must use will be given to you in advance by your instructor. Your detailed design will depend a lot on the rubber bands supplied.

We’ve a tradition at hypography of not directly giving answers to problems or design for class assigned projects, but giving hints and feedback, so I’ll stop hinting now. *boongee, see if the hints you get here allow you to come up with a design that does what you need, then post it here, and we’ll give your our opinions about how well it will work.

[*boongee]

^ thnx CraigD! yeah, we were planning on having something push the coin off, i just wanted to see what other people came up with =P

seeing what you were thinking, is really simillar to what we are going to do, i'll go with that plan =D thnx for the confirmation =D

Cap'n Refsmmat-- i didn't want to outline my plan because i didn't want people to feel too restricted in a 'box' =P but thnx for posting<3

thnx for all the help! i'll post up the results of my project when im done

thnx again<3