Performance Test.
Title: Catapult Calculations
Description: Each student will design and construct a working catapult that will launch a large marshmallow the farthest distance possible along the straightest path possible. Each student will calculate the amount of work done by their catapults.
Materials:
1 - wood dowel, metal or wooden spoon, or any thing that can be used as a fulcrum
1 - base for your catapult (box, or container)
Power source - weights, rubber bands, bungy cord
Tools to build catapult (i.e. hammer, saw, screwdriver)
Metric measuring tape or range finder
Spring scale in newtons. If unavailable, use a spring scale in pounds and convert.
Time Required: 1 class period to collect and calculate data (45 minutes) This performance test requires each student to build a catapult before this class period.
Student Background needed: A lesson on simple machines and specifically on levers are needed.
Notes to teacher.
This is a great way to demonstrate kinetic and potential energy as well as simple machines. This performance test also allows the students measure quantitatively the amount of work being done. Remind student to be careful when using tools to build their catapults.
Procedures
1. The dimensions of the catapult will not exceed one cubic feet (12" high X 12" wide X 12" deep) in size for the base. The Lever arm may not exceed 2 feet.
2. Students may power their catapult by various measurable means. Such as rubber bands, counterbalance weights, or elastic lever arms. They may not hit a portion of the lever arm to power their catapult. This would be difficult to measure.
3. Day of class. Have student measure the force of their catapults in lbs. Have them convert to newtons
4. Have student classify their catapults as a 1st, 2nd, or 3rd class lever.
5. Go out side or in the foyer. The higher the roof, the better.
6. Have students launch their catapults using a large marshmallow. Record the distance in meters. Repeat to allow two attempts.
7. Calculate the amount of work done by catapult.
Sample Scoring Guide.
1. Successfully building their catapult ...... 25 pts
2. Successfully calculating the amount of work done by catapult . . . 15 pts
3. Catapult has thrown a minimum of five feet ...... 5 pts
4. Student are on task ...... 5 pts
Catapult Data Sheet (Student Worksheet)
Activity Sheet
Name ______Period ______
Your catapult is a simple machine, a lever. You must identify the class of lever your catapult falls in. When throwing a marshmallow, your catapult is doing work. In this activity you will calculate the work being done by your catapult and the mechanical advantage of your machine. To accomplish these tasks you will need to listen to the instructions given by your teacher.
My Catapult is a _____ Class Lever
MA = Effort arm length / Resistance arm length
Length of effort arm ______cm.
Length of resistance arm ______cm.
Mechanical Advantage ______
Work = Force x Distance
Force ______N. Distance ______m. Work ______J.
Scoring Guide.
1. Successfully building your catapult ...... 25 pts
2. Successfully calculating the amount of work done by catapult . . . . 15 pts
3. Catapult has thrown a minimum of five feet ...... 5 pts
4. On task throughout the activity...... 5 pts