Which move gets the player there faster, head-first or feet-first slide?
The head-first slide is faster, according to David Peters, a mechanical engineer specializing in aircraft and helicopter engineering and a professor at Washington University in St. Louis. Peters is also a long-time baseball fan who analyzes the game not on the usual statistics but on the applications of math and physics.
Peters looked at three mathematical issues affecting the player’s speed during slides:
* Momentum, determined by the mass of the player’s body times his running speed.
* Angular momentum, which is mass movement of inertia times rotational rate. A player starting to slide feet-first is likely to rotate clockwise; one moving into a head-first slide is likely to rotate counter-clockwise.
* Newton’s Laws, force equals mass times acceleration and moments of inertia times angular acceleration.
Peters says the key is the location of the player’s center of gravity. The center of gravity is that point where the player’s weight is equally distributed — half above and half below the point. It is normally above the body’s actual halfway point.
Using a head-first slide could slice 1/200th of a second in travel time to the plate. That translates into about five inches ahead of feet-first slides. The player gains more forward momentum when sliding head-first.
Peters believes there are statistics that indicate 60 percent of base runners get to base faster when they go for the head-first slide.
But there is one caveat, says Peters.
The head-first slide exposes the player’s head and hands to injury, and may therefore be dangerous to the player.
The feet-first slide can also be dangerous — to the player in the opposing team. It is said baseball great Ty Cobb used cleats with sharpened spikes to scare away anyone who wanted to stop him from completing a slide.
An alternative is run; don’t slide to base — especially first base. Mathematically, when you slide you lose forward velocity because you can no longer pump your legs. But when you’re running, you push your feet out in front of the center of gravity and gain a three-step advantage.
There may only be one advantage of sliding into first base: it gives you the chance to evade the first baseman’s tag.
* Avoid head-first slides. The risk of injury is greater, especially for children.
* Make sure your child’s coach trains the players how to avoid injury, e.g. when pitching, sliding, or dodging a ball thrown directly at them while at bat.
* Encourage use of breakaway bases, to prevent injuries during slides.