Help with a grade 12 physics project — small recoil powered car

[CheatCod]

Summary:: We have to make a car which
-Has to have a trigger mechanism
-after 5s the car launches a projectile backwards to push the car forwards at least 6m
-NO ELECTRICITY ALLOWED, no motor, timer, etc
-weight limit of 1kg

Here it goes, we have to create a car powered solely by gravitational or elastic potential energy, so no electricity allowed. It must have a trigger mechanism, which can be anything you'd need to do to get the car going. Once you triggered the car, you aren't allow to touch it anymore, and after 5 second after triggering, the car shoots out a projectile backwards which propel the car forwards at least 6 meters. The car can only move from the projectile firing backwards, the projectile can be fired using either gravitational or elastic potential energy.

I've been scratching my head at this for some time now, anyone got any creative idea that's reasonable to implement?

 

[scottdave]

Trebuchet or catapult would be 2 ways. Or a wind up device. Start with some calculations - how fast do you need to launch a projectile?

 

[berkeman]

Welcome to the PF, @CheatCod

Looks like you and this other person are in the same class? Or at least have the same project...

https://www.physicsforums.com/threa...competition-please-self-propelled-car.981197/

 

[DEvens]

Your user name is CheatCod? And you want us to do your homework for you? Ok then.

 

[berkeman]

I thought that was a little ironic as well...

 

[CheatCod]

Welcome to the PF, @CheatCod

Looks like you and this other person are in the same class? Or at least have the same project...

https://www.physicsforums.com/threa...competition-please-self-propelled-car.981197/

Ah yes, we have the same teacher but different class.

 

[CheatCod]

Your user name is CheatCod? And you want us to do your homework for you? Ok then.

Sorry for the misunderstanding, I came up with several ideas and experimented a bunch beforehand, none of them worked that well. I didn't post it because I thought it's not relevant. Will update post

 

[berkeman]

Sorry for the misunderstanding

I can change your username for you if you like. Just let me know what you would like it changed to.

 

[CheatCod]

Thank you so much but that's fine haha, I like my username as it is

 

[berkeman]

Well, okayyy.

:-)

 

[CheatCod]

Summary:: We have to make a car which
-Has to have a trigger mechanism
-after 5s the car launches a projectile backwards to push the car forwards at least 6m
-NO ELECTRICITY ALLOWED, no motor, timer, etc
-weight limit of 1kg

Here it goes, we have to create a car powered solely by gravitational or elastic potential energy, so no electricity allowed. It must have a trigger mechanism, which can be anything you'd need to do to get the car going. Once you triggered the car, you aren't allow to touch it anymore, and after 5 second after triggering, the car shoots out a projectile backwards which propel the car forwards at least 6 meters. The car can only move from the projectile firing backwards, the projectile can be fired using either gravitational or elastic potential energy.

I've been scratching my head at this for some time now, anyone got any creative idea that's reasonable to implement?

I can't seem to edit my og post but here are some of my ideas so far:
- a mousetrap launcher attached to a low-friction, customized car. For the timer, I'll use parts from a music box which would gradually tense up a string attached to the mouse trap's trigger mechanism
-a spring canon mounted to a car, but I've got no idea how to use a music box to trigger it.

I've experimented with a mousetrap launcher but it doesn't seem to be powerful enough to propel the car more than half a meter away.

 

[CheatCod]

Trebuchet or catapult would be 2 ways. Or a wind up device. Start with some calculations - how fast do you need to launch a projectile?

I've done some very rough calculation. It seems like with a average car design I'd need the projectile to reach around 10m/s