I just heard McReynolds make the comment "the grass accelerated the car." When will this misconception go away?

I remember debating this years ago with a well know eastern motorsports writer on Compuserve after Buddy Baker said the same thing (believe he was talking about Daytona before they took out the grass between turn 4 and the pits.)

I know it's silly, but the only way a car would accelerate on grass (or ice, or mud, or water) is if the driver is on the gas with the car pointed in a forward direction.

I think he he simply means the grass having less friction than asphalt (or gravel) doesn't decelerate the car as much as those surfaces would, hence it 'accelerates' the car, in his words, lol.

Yes, I know he's smart enough to understand the simple physics -- I'm just surprised at how many times that gets said.

I think the perception comes from the change in deceleration. A car sliding on pavement is decelerating at, let's just say, a rate of x. When it hits grass it's rate of deceleration slows to, let's say, y. It's not speeding up, it is just not slowing down as quickly and the body which suddenly goes from maybe .5 G's of deceleration to maybe .1 G interprets it as an increase in speed. The perception is all a product of the G forces.

Is it possible he was being sarcastic?

I don't think he was being sarcastic. I hadn't heard it for a few years but it used to be mentioned quite a bit, even to extremes like "when the car hits the grass it speeds up....".

I'm sure it originated from the perception that a car speeds up when it spins onto a grassy area.

I remember a few years back when they ran the Copperworld Classic at Phoenix. The Southwest Tour cars would run and they were about the same speed as the Cup cars. Then the IRL cars came out and it took several minutes for my eyes to adjust to the cornering speed. It seemed like an optical illusion on how fast they drove into the turns. In a few minutes they looked normal.

It was just funny to hear that again.

JDeee - 07 August 2009 09:23 PM

I don't think he was being sarcastic. I hadn't heard it for a few years but it used to be mentioned quite a bit, even to extremes like "when the car hits the grass it speeds up....".

I'm sure it originated from the perception that a car speeds up when it spins onto a grassy area.

I remember a few years back when they ran the Copperworld Classic at Phoenix. The Southwest Tour cars would run and they were about the same speed as the Cup cars. Then the IRL cars came out and it took several minutes for my eyes to adjust to the cornering speed. It seemed like an optical illusion on how fast they drove into the turns. In a few minutes they looked normal.

It was just funny to hear that again.

Oh come'on, Nascar Cup cars can defy physics can't they?

JDeee - 07 August 2009 09:23 PM

I don't think he was being sarcastic. I hadn't heard it for a few years but it used to be mentioned quite a bit, even to extremes like "when the car hits the grass it speeds up....".

I'm sure it originated from the perception that a car speeds up when it spins onto a grassy area.

I remember a few years back when they ran the Copperworld Classic at Phoenix. The Southwest Tour cars would run and they were about the same speed as the Cup cars. Then the IRL cars came out and it took several minutes for my eyes to adjust to the cornering speed. It seemed like an optical illusion on how fast they drove into the turns. In a few minutes they looked normal.

It was just funny to hear that again.

I recall hearing a baseball commentator explaining why a players change up pitch was so hard to hit. It "speeds up" on the way to the plate.