Popsicle Catapult
Challenge: To design the best Popsicle catapult possible.
Parameters: You will need to make a Popsicle catapult with at least 10 popsicle sticks, up to three #33 standard latex elastics, masking tape, glue, paper clips, foam board, and string. The projectiles will be 6.0 mm plastic BBs, of which you will be able to launch 20. You can hold or clamp your catapult against your desk. Your target will be a standard 4.0 L ice-cream bucket exactly 4.00 m away, at the same level as your desk.
Scoring: Your launcher will be scored on several parameters, some of which you want to maximize, and others you want to minimize:
Mass of Launcher score (m) is mass in grams, no less than the mass of ten popsicle sticks
Direct hits (d) is shots that go in the bucket
Bounces (b) are shots that bounce off the outside wall of the bucket
Formula: (5•d + 2•b + 1) / m
Rank will be based on score, with highest score earning highest rank.
Physics: The path of a dense projectile upon release is approximately a parabola. The initial velocity and launch angle are mathematically related to the maximum height and horizontal displacement. In fact, every aspect of the motion can be calculated at the high school level. This is because we can assume the horizontal motion exhibits constant velocity while the vertical motion exhibits constant acceleration due to gravity, and that those two components are independent of each other.
Extensions: You should be able to describe the velocity of the projectile at any moment in time, and be able to hit any target at any position, not just at the same level.
Help/Hints: Getting the best result will involve achieving a large initial velocity at a precise and repeatable angle, and knowledge of the path through the air.
All moving parts should be as light as possible so that less energy is wasted as kinetic energy of your launcher. Budget lots of time to practice using your device to reduce the impact of human factors.
Quiz Topics: Two Dimensional Kinematics and Dynamics
Online Text: ch 2, 3, 4, 5