Prompt: How far would you have to pull the car back in order to get it to go 100'?
Materials: Toy cars, meter sticks.
Hand them the cars, ask the question and get out of the way.
But Mr. Cox, the farthest we can get the car to go is around 10'. We can only pull it back so far until it starts clicking.
Right. So if you could build a car that could be pulled back farther, how far would you need in order for the car to go 100'?
Mr Cox, what do we do if our car keeps turning?
The two groups that had problems with the car came up with two different solutions. One group decided to tie a piece of string to the spoiler and measured the amount of string the car pulled past the starting line and the other group simply estimated by breaking the curve down into short line segments. (Oh man, do you guys just realized you set me up for a lesson plan in May? Can you say calculus?)
Mr. Cox, if I pull the car back 3", it goes 30", but if she pulls it back 3", it goes 36". Why?
Turns out that one kid pushed down on the car harder than the other which kept the tires from sliding.
I'm not sure if it is supposed to be or not, but the data was pretty linear. One student wondered why it would be linear since the car takes time to speed up and slow down and the shorter distance it travels, the more energy it is using to simply get up to speed.
Reason #421 Twitter is awesome
I tweet some pics of the activity and Frank asks me if I'm going to have a contest to see which group can get their car closest to the line.
*ahem* Of course I'm going to have a contest at the end to see who can best predict the distance their car travels.
Three groups were able to get within 1.5". (Two of them were the groups whose cars turned). The best was this: