How to Calculate the Distance for a Catapult Launch

Catapults use force to hurl objects over walls.

Catapults can be effective weapons for throwing stones at or over walls, as was often done in the Middle Ages. Nowadays we don't use catapults in this fashion, but you can learn something about physics by calculating the distance a projectile travels using a model catapult.

Things You'll Need

• Model catapult
• Projectiles of various weights
• Measuring tape

Instructions

1. Test the launching distance by conducting at least 10 trials. Conduct each trial in the same conditions if possible: keep the catapult in the same place, use the same projectile and launch it under the same wind conditions. Measure the distance the projectile travels in meters and write it down for each trial.

2. Determine the average distance the projectile travels by adding the average distances for each trial and dividing by 10.

3. Repeat the experiment with projectiles of varying weights to determine how weight affects the distance the projectile travels. Vary the design of your catapult--the length of catapult arm or the angle of launch--to determine how these factors affect launch.

References

• Science Buddies: Effect of Trebuchet Arm Length or Counterweight Mass on Projectile Distance