• To the casual observer, a lacrosse ball and field hockey ball may seem like the same thing. They're about the same size, they're both usually white, and they're both solid enough to cause some severe pain when they whistle off an exposed thighbone. There are, however, some subtle differences in the size, weight and construction of the two.
  
  

Lacrosse Balls

• The NCAA revised its specs on what constitutes a regulation lacrosse ball in 2000. According to Section 17 of the NCAA rulebook , a regulation ball must meet the following requirements:
  
  Surface: smooth
  Construction: solid rubber
  Colors: white, yellow or orange
  Weight: 5-5.25 ounces
  Circumference: 7.75-8 inches
  Diameter: 2.47-2.54 inches
  Coefficient of restitution: 0.597-0.708 at 65 degrees Fahrenheit
  
  The coefficient of restitution is the "bounciness" of a ball. In this case, a lacrosse ball dropped from 72 inches must rebound 43 to 51 inches after impact.
  
  

Field Hockey Balls

• The NCAA respects the specifications set forth by FIH, the International Hockey Federation, and uses the Kookaburra Dimple ball as its standard. Most national teams also use the Kookaburra ball. The specifications for these balls are set in metric terms as follows:
  
  Surface: smooth with small dimples or indentations
  Construction: plastic shell over a quilted center
  Colors: white or orange
  Weight: 156-163 grams (5.50-5.75 ounces)
  Circumference: 224-235 mm (8.82-9.25 inches)
  Diameter: 71.30-74.80 mm (2.81-2.94 inches)
  
  

Differences in Play

• The different construction of each ball leads to differences in how the ball travels or is played in the course of a game. For instance, a field hockey player can shoot the ball to travel about 45 to 60 mph. Since it is played off the ground, thick or wet turf can slow that speed considerably. On the other hand, a lacrosse player can shoot the ball in excess of 100 mph, using a sidearm crank or quick shot. With that in mind, an amateur physics student can deduce the most obvious difference--lacrosse balls travel and make contact with almost twice the force of a field hockey ball.