Catapults & Projectile Motion


Duration: 3-5 hrs

GRADE LEVEL
Middle School (ages 11-13)
High School (ages 14-17)

DIFFICULTY
Intermediate

SUBJECT
Engineering
littleBits Basics
Math
Physical Science
Social Studies
Technology
Robotics
Earth & Space Science

MODULES & ACCESSORIES USED (7)
button (1)
power (1)
servo (1)
mounting boards (1)
glue dots (1)
servo mount (1)
mechanical arm (1)

OTHER MATERIALS USED (6)
assorted masses 1-50 grams 1
meter stick 1
Screws 1
Tape 1
hot glue gun and glue 1
dram cup 1

TOOLS USED
screw driver

LESSON GUIDE

STEP 1 : INTRODUCE

Catapults

Catapult Schematic

Introduce the challenge: design and build a catapult prototype to explore…

– How is the distance traveled by the projectile affected by the length of the arm?

– How is the distance traveled by the projectile affected by the mass of the projectile?

– How is the distance traveled by the projectile affected by launch angle of the arm?

Introduce/review the concept of a variable:

A variable is something in a system that can be changed. In an experiment, only one variable can be changed at a time.

Possible variables in this investigation: 1. length of throwing arm, 2. mass of projectile, 3. angle of release

Introduce/review the concept of correlation: A correlation is a statistical relationship between two attributes in a system where one attribute causes a change in another attribute. If a strong correlation exists, the outcome of one attribute can be predicted by another.

STEP 2 : CONNECT

Return to the challenge: design and CREATE a catapult prototype to explore…

– How is the distance traveled by the projectile affected by the length of the arm?

– How is the distance traveled by the projectile affected by the mass of the projectile?

– How is the distance traveled by the projectile affected by launch angle of the arm?

Refer to the “Invent a Self-Driving Vehicle” challenge in the STEAM Student Set if your students need some guidance.

STEP 3 : TEACH

Working first in small groups, students will develop their hypotheses and brainstorm methods for investigating the challenge questions. Return to whole group to share ideas as a class and develop a standard procedure for data collection.

STEP 4 : ENGAGE

Catapults1

Create Prototype:

Working in small groups, students will design and build a catapult that can be used to collect the data needed to answer the challenge questions.

Create Measurement Procedures:

As a class, determine what data will need to be collected to answer the questions above.

Suggested methods:

– Distance: place a meter stick or measuring tape on tabletop or floor with catapult at the end.

– Release Angle: use a protractor with the vertex point positioned at the axel of the servo motor (pivot point).

– If available, capture photographs or video of launches. Video can be analyzed frame by frame to chart the projectile’s path.

STEP 5 : PRACTICE

Catapults2

Catapults3

Play & Remix:

Catapult prototypes are tested and designs are refined.

Data is collected through a number of experimental trials where the length of the throwing arm, the mass of the projectile and the angle of release

Students design and build a catapult prototype using a mechanical arm.

Test designs with projectiles of 5-10g mass.

Refine/revise designs.

Investigate:

– How is the distance traveled by the projectile affected by the length of the arm?

– How is the distance traveled by the projectile affected by the mass of the projectile?

– How is the distance traveled by the projectile affected by launch angle of the arm?

Make predictions. Collect data as a class of all trials and variable iterations.

STEP 6 : CLOSE

Share:

Organize data in a spreadsheet. Produce x-y scatter plots of the three variable iterations. construct graphs by group graph class means – combine class data and compute class means for each variable iteration. Analyze data (answer investigation questions).

Conclusions & Reflections:

Is the distance traveled by the projectile affected by mass of the projectile, length of the throwing arm or angle of launch release?

How do the data and conclusions compare to your predictions?

What might be some reasons for any differences?

STEP 7 : EXTENSIONS

Taking it Further: Given the data, what is the ideal design for a littleBits catapult? Build and test the prototype if time allows.