Catapult

Objective

To build a catapult from toothpicks that will hurl a steel ball.

Permitted Materials

1. standard wood toothpicks (round or flat)
2. casein glue (Elmer’s, Borden’s, etc.)
3. dental floss (waxed or plain)

Other types of string, sticks, or glues (epoxy, rubber, super, etc.) will not be allowed.

Other Constraints

The catapult must have a cocking mechanism (typically, a floss string which can be cut with a scissors or pulled downward by hand). Pulling a string cannot be used to provide additional propulsion. Only the permitted materials may produce propulsion.

When cocked, the catapult must fit completely in a box 30 cm. X 30 cm. X 30 cm.

When cocked, the catapult must be able to hold, without assistance, a 1.6 cm. diameter ball bearing projectile.  The projectile will be furnished by the judges.

When firing, just one contestant may steady the catapult and cock it.

Testing Procedure

The catapult will be placed on the floor and fired. Measuring the distance the projectile lands along a straight line marked on the floor, and then subtracting the perpendicular deviation from the straight line, will determine the score.

Contestants will have three attempts. The best of the three will be used as the final score. The three attempts will be scheduled consecutively; however, contestants may opt to delay the third attempt to make minor repairs or adjustments. In the event of a tie, the second best of the three attempts will be the tie breaker.

Practice runs in the testing area, prior to the actual competition, will  not be allowed.

College of Saint Benedict
Saint John’s University

Jim Crumley
Chair, Physics Department
SJU PEngl 107
Physics Department
320-363-3183

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