The goal is to make it move down the track the fastest, and cars compete four at a time in 64 heats to determine the top three fastest. The Pinewood Derby cars are made from a block of wood with four wheels, and each participant can decorate it to look like anything he wants, as long as it weighs 5 ounces or less. Joseph Kaplow’s car won first place with a speed of 159.25 miles per hour Carter Teese came in second and Gabriel Tischio rounded out the top three. 27, for its annual Pinewood Derby, racing down a track to determine the fastest homemade cars. What if you have two identical cars, but one has a little bit better lubrication on the axle? Instead of coefficient of friction at 0.05, how about 0.NUTLEY, NJ - Nutley’s Cub Scout Pack 141 returned to the John H. That is pretty darn close (that is official Pinewood Derby lingo). Both cars have the same mass, same wheels, and same cross sectional area. One with a drag coefficient of 0.35 and one that is a little better with a coefficient of 0.34. The block car would be 5 cm behind the car looking car.Īlthough these times are quit similar, maybe looking at the distances is a little easier. I won't show you the graph (boring) but I will tell you the two times: 1.961 seconds and 1.947 seconds. This might give it a cross sectional area half as much as the block with a drag coefficient of 0.35. The drag coefficient is lower and the cross sectional area is smaller. one that is all aerodymaicalsized but with the same mass? Two things happen. What about shaving it down? What if I make a run with a plain wood rectangular block vs. The more massive car had a time only 0.008 seconds less than the lower mass car and finish about 3 cm ahead. I zoomed in on the last 0.3 meters of the track so you could see the difference. One has a mass of 0.142 kg and the other just 0.100 kg. In this run, I have two plain rectangular blocks.
Here is the output from my first calculation. A super nice car might have a drag coefficient around 0.35 ( from wikipedia). For the drag coefficient, if it was an unaltered block of pine, it might have a C around 1.The mass of the car is 142 grams (actually, I will run one car with a mass of 100 grams).After that, it is level for about 4 meters (my guess from looking at images online). The track is a slanted part that is 30 degrees at about 2.5 meters long.I will assume that the rolling friction doesn't do anything.
Also for friction, I am going to assume that this is just normal kinetic friction from the axles.Coefficient of kinetic friction is about 0.05 - I mostly just made that up.However, I don't want to deal with wheels right now.
I am going to assume that there is no rotational energy going to the wheels. I will make a model for a car rolling down a straight track. There is a quick and easy solution, a numerical calculation ( here is a link to introduction to numerical calculations) In this case, the forces (and thus the acceleration) depend on the velocity. Normally, you calculate the forces and acceleration and then you can find the motion of the car since the acceleration would be constant. But how much does air resistance make mass matter? Motion of a car with air resistance is slightly tricky (but not impossible).
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