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Marlington Physics



Catapult Project Guidelines


You have the task of constructing a projectile launcher (a.k.a. catapult) capable of launching a ping-pong ball accurately and as far as possible.

Construction Guidelines

  • The catapult must fit into a 50 cm cube and have a firing mechanism that locks in place. Students should be able to ready the catapult for launch in under one minute.
  • The catapult must use mechanical energy stored by the students during the allotted one minute setup time (i.e. outside energy sources such as chemicals or batteries are not permitted). Air-powered ball launchers will not be permitted.

Competition Goals

This event has two portions — accuracy and distance. You must enter the same catapult in both sub-events. Your total score will be the sum of the scores from the two sub-events. The projectile itself will be a ping-pong ball and all “hits” are defined to be the initial point of impact (bounce and roll does not count). You will have one minute to prep your catapult before each shot. After one minute, the shot is disqualified and receives zero points. An unmodified ping-pong ball must be used and it must travel through the air by itself (i.e. the ball may not be launched inside a carrier).


A circular piece of cardboard (roughly the size of a large pizza) will be placed on the floor at a distance between 2 m and 8 m (to be determined the day of the competition) from the launch line surrounded by a one square meter secondary target (which you may position as desired). You may measure the distance and then get one shot to hit the target.

  • A direct hit scores 60 points.
  • A hit on the secondary target scores 40 points.
  • Misses outside the secondary target will score 20 points minus the number of decimeters to the secondary target area. Negative scores will be recorded as zero.
This process will be repeated twice (three shots total, each at a different distance) and your score for this portion of event will be the total points scored on all three shots.


You will get three shots to shoot the projectile as far as possible with the best shot determining your score. If the projectile hits the ceiling or wall, the distance will be marked at that point. You will receive 1 point for every decimeter of flight.
Since this is a competition, project scoring will be partially determined by finishing position. The more points you score, the better you will place!

Group Details

You may work in groups of up to three on this project but groups are not required. If any member of your group does not contribute their fair share, please send me an e-mail.


Half the grade on this project will be based on the results of the competition. The catapults will be ranked by total points earned in the competition. The top scoring catapult will receive 50/50 points. Each position down in the finishing order will correspond to a drop in points for this portion of the grade.

The second half of your grade will be based on the design and testing of the catapult. Inventive or unique designs will score much better than rat traps stapled to a board. You should also provide some sort of data table as evidence of your test firing. The more evidence you provide of effort in the design, construction and testing portion of the project, the better you will score.

Competition Day

Catapults are due the first day after spring break. Students not present that day must have someone bring their catapult and fire it during the competition or forfeit. NO LATE CATAPULTS WILL BE ACCEPTED!!


Last updated on 02/26/2007