It All Depends on the Trajectory

  Snickers has quite a knack for coming up with deep philosophical questions. His latest went something like this:

"What's more dangerous - concrete or asphalt?"

I don't usually think about concrete or asphalt much. And when I do, it's not in terms of danger. But if you're a scooter rider who's taken a few tumbles it's an important subject. Do I aim for the concrete gutters? Or the asphalt? The correct answer is the grass! But if it's not available, which one is a better choice.

We came up with the following extensive list of pros and cons:

Concrete
Pros: Smoother than asphalt.
Cons: Harder than asphalt (but not by much).

Asphalt
Pros: Softer than concrete (but not by much).
Cons: Rougher than concrete.

So, is it better to slide across concrete when flying out of control off a wheeled aparatus or better to slide across asphalt? I suppose it all depends on the trajectory. Are you sliding low and fast like you're sliding into first base? Are you coming from up high and bouncing a few times before stopping? Is there any rolling involved? What about torque and energy, mass and velocity?

Suddenly there is too much physics involved! How about we just avoid the asphalt, concrete, bricks and sewer grates altogether and aim for the grass.

Quack!