Physics 2nd
Six Weeks Project: Catapult Contest
I. Purpose: To design a catapult powered solely by two mousetraps that will throw a standard hacky sack the greatest distance along a specified line.
II. Materials: Two standard mousetraps, other materials for framework of catapult, standard hacky sack for testing
Specifications:
1. Students may work individually or in pairs on this project. If students wish to work together, they must sign up with their teacher by 9/24. After this date, no further changes may be made. If students work as a pair, one catapult is submitted. One report may be submitted for both students, or they may choose to submit individual reports.
2. The power for the catapult is to come from the spring(s) of one or two standard sized mousetraps only. No other stored energy source may be released by the trap springs, and the springs must be at ambient (room) temperature. Only commercially available mousetraps may be used.
3. The springs may not be altered in any way. The arm and the board may be altered. However, the spring must remain attached to the original board, and there must be sufficient board material remaining so that the parts are easily recognizable. The spring and the arm attached to the spring may not move through an angle of more than 180 degrees.
4. If an arm is attached to the mousetrap spring mechanism, the arm must be sufficiently rigid that no energy is stored in the arm itself.
5. The mousetrap spring and attached wire frame may not be cut or altered. However, the spring may be released by some mechanism other than that originally used on the mousetrap.
6. The whole catapult must be constructed so as to be carried by one individual and must rest on the ground. No external weights may be added for stability. The entire assembly must be no more than 38 cm (15 in) on a side. This will be tested by placing the catapult into a box 15 in (38 cm) on a side. Points will be deducted for any part of the catapult sticking out of the box. The catapult may be in the cocked or released position for this measurement.
III. Procedure: Build a catapult that fits the above specifications. Use any materials you like for the framework of your device. In a short paper, typed and using the lab report format, detail the construction and testing of your catapult and note any modifications you made. At least three tests should be made at home with the distances measured and recorded in the data section. Discuss the physics of the catapult and the resulting projectile motion of the hacky sack in your conclusion. Be sure to use any physics topics covered in class in your discussion. Bring your catapult and your typed paper to class on Monday, 10/22 for the contest. Each catapult will be fired three times down a range marked by a centerline. Hacky sack projectiles will be provided. Each team will have a maximum of three minutes to set their catapult in place, aim it, and fire up to three times. No part of the catapult may extend beyond the firing line, either before or after the launch, including the throwing arm, or that shot will be disqualified. After the testing, add the distance data and score to your paper and turn in.
IV. Data: Construct a suitable data table for your trials at home (at least three) and at school (up to three). Be sure to include the distance, the deviation from the centerline and the score, calculated according to the following formula: SCORE = DOWNRANGE DISTANCE - DEVIATION DISTANCE. The downrange distance will be the perpendicular distance from the firing line (or its extension) to the impact point of the hacky sack. The deviation distance will be the perpendicular distance from the centerline to the impact point of the hacky sack. The best score for the three shots at school will be used for grading purposes.
V. Conclusion: The conclusion should include the following elements:
§ An evaluation of your catapult and a prediction of its performance.
§ A description of modifications made including the reasons for them and the result of them.
§ A discussion of projectile motion, including the horizontal and vertical velocity components, the type of motion in each dimension, the range of the projectile and its dependence on launch angle.
§ A discussion of the physics involved in catapult operation including the work input, the potential and kinetic energy, the mechanical advantage and the efficiency of the machine.
Name____________________________
Per. _________ Date_________________
Evaluation Guidelines
(Major Test Grade)
The Paper
Energy, work, power
Efficiency, mechanical advantage
Velocity vectors
Horizontal and vertical motion
Range, launch angle
Prediction
Typed
Spelling, grammar, sentence structure
The Catapult
Detailed list
Trap type and condition
Creativity
Functionality
Stability
Trials Documented
(Max = 10) __________
Suitable data table
Performance Score
(Max = 10) __________
(Best score / class best score) x 10