Any Other Pinewood Derby Dads?

[SPYDERLK]

Why are the weights put in the back of the car?
larry

 

[Iplayfarmer]

Why are the weights put in the back of the car?
larry

I think the theory is that they are higher up when the car starts. Therefore, they have more potential energy. For that split second when the cars are leveling out from the "hill" onto the straight track, the cars with weight further back will be pushing for a split second longer.

I don't know if that really helps at all, but that's the theory.

 

[MossRoad]

I think the theory is that they are higher up when the car starts. Therefore, they have more potential energy. For that split second when the cars are leveling out from the "hill" onto the straight track, the cars with weight further back will be pushing for a split second longer.

I don't know if that really helps at all, but that's the theory.

That's exactly the theory. Once the car turns the bend at the bottom of the hill it starts losing energy. So, the longer it is falling down, the more energy it builds up. You just have to keep enough weight in front of the rear axle so that the car does not tip backwards on its butt and create drag.

I read an interesting explanation about stored energy and pinewood derby cars. It went something like this...

Some smart dads know that in a vacuum, a feather and a bowling ball will fall at the same rate, so weight in a pinewood derby car really doesn't matter. So take a bowling ball and a feather and drop them in a vacuum. They will land at the same time. However, before you begin, put an egg under each one.... the bowling ball has much more stored energy and will crush the egg. Same thing applies to pinewood derby cars. Once they finish dropping down the track and start rolling it is the stored energy that keeps them moving forward.

The car with the most weight that falls the longest with the least amount of resistance from the friction of the wheels on the track and axles will probably win. Wind resistance on pinewood derby cars ranks far down the list of problems to overcome.

If your derby allows longer cars, use the maximum length with the weight as far back as possible. It falls longer, so it stores more energy. Our derby had car length, width and height rules, so it wasn't a problem for us. The playing field was extremely level. :thumbsup:

 

[SPYDERLK]

I think the theory is that they are higher up when the car starts. Therefore, they have more potential energy. For that split second when the cars are leveling out from the "hill" onto the straight track, the cars with weight further back will be pushing for a split second longer.

I don't know if that really helps at all, but that's the theory.

That's exactly the theory. Once the car turns the bend at the bottom of the hill it starts losing energy. So, the longer it is falling down, the more energy it builds up. You just have to keep enough weight in front of the rear axle so that the car does not tip backwards on its butt and create drag.

I read an interesting explanation about stored energy and pinewood derby cars. It went something like this...

Some smart dads know that in a vacuum, a feather and a bowling ball will fall at the same rate, so weight in a pinewood derby car really doesn't matter. So take a bowling ball and a feather and drop them in a vacuum. They will land at the same time. However, before you begin, put an egg under each one.... the bowling ball has much more stored energy and will crush the egg. Same thing applies to pinewood derby cars. Once they finish dropping down the track and start rolling it is the stored energy that keeps them moving forward.

The car with the most weight that falls the longest with the least amount of resistance from the friction of the wheels on the track and axles will probably win. Wind resistance on pinewood derby cars ranks far down the list of problems to overcome.

If your derby allows longer cars, use the maximum length with the weight as far back as possible. It falls longer, so it stores more energy. Our derby had car length, width and height rules, so it wasn't a problem for us. The playing field was extremely level. :thumbsup:

Yes. :thumbsup: ... I just thot the reason should be stated here and nobody had said anything. ... Its the level coast out at the bottom that favors the rear weight proportion. A car that leads down the hill but loses out at the bottom coast was set up very right friction wise. It lost the race by not storing as much potential to be converted to kinetic. Height of the weight above the surface is another factor, aiding by a different mechanism; high weight actually moving more rearward relative to the CG as the car levels out. Every little bit helps.
larry

 

[MossRoad]

O.K. Here is a 27 part lecture on pinewood derby cars. Increadible, but true, there is stuff in here that makes perfect sense once you think about it. I used just a couple examples in here to explain to my daughter why we should.... "Sweetie... wake up sweetie. This is important." build the car like these guys say... :laughing:

Pinewood Derby Physics Lectures

Really, though, if you want to know why some things work and some things don't this pretty much explains it all. Good read for those that are interested. Increadibly boring for most kids. :thumbsup: