Tag Archives: physics

How to hit a baseball travelling at the speed of light

It seems obvious that you can’t do this. XKCD does the math (or physics) to demonstrate that not only is it impossible, it’s also fatal for pitcher, batter, and probably the entire city…

“After about 70 nanoseconds the ball arrives at home plate. The batter hasn’t even seen the pitcher let go of the ball, since the light carrying that information arrives at about the same time the ball does. Collisions with the air have eaten the ball away almost completely, and it is now a bullet-shaped cloud of expanding plasma (mainly carbon, oxygen, hydrogen, and nitrogen) ramming into the air and triggering more fusion as it goes. The shell of x-rays hits the batter first, and a handful of nanoseconds later the debris cloud hits.”

mushroom cloud

It’s not all bad news though. The batter gets on base.

A careful reading of official Major League Baseball Rule 6.08(b) suggests that in this situation, the batter would be considered “hit by pitch”, and would be eligible to advance to first base.

I love this stuff. The XKCD “What If” blog is tackling similar questions on a weekly basis. Like trying to figure out how much power Yoda could generate via the Force.

Free Kick Physics

Roberto Carlos, a Brazillian defender famous for belting free kicks with incredible control (as opposed to Beckham who tended to go for placement over power), hit a pretty memorable free kick against France in the 1998 World Cup. The video is below.

The kick seems to defy the laws of physics. So some scientists have built an equation to explain it. Their work has just been published.

“We discuss the trajectory of a fast revolving solid ball moving in a fluid of comparable density. As the ball slows down owing to drag, its trajectory follows an exponential spiral as long as the rotation speed remains constant: at the characteristic distance where the ball speed is significantly affected by the drag, the bending of the trajectory increases, surprisingly. Later, the rotation speed decreases, which makes the ball follow a second kind of spiral, also described in the paper. Finally, the use of these highly curved trajectories is shown to be relevant to sports.”

Image Credit: Wired Magazine’s story on the study.