Lesson Write-Up For Fall Quarter 2011

Your name: David Luong

Title of Lesson:Angry Students

Grade Level: Junior & Senior

Subject(s): Physics

Summary:

Angry students, armed with Physics knowledge, conspire to exact revenge on their grade-robbing teachers, Angry Bird style! Projectile motion is the name of the game. Will the teachers receive a taste of the subject they have been preaching all semester long? Students armed with water balloons and a rubber band launcher perform calculations using a given launch angle and measured launch velocity to predict where the balloon will land. The teacher will be asked to stand at that location.

Time Required: 1.5hrs

Group Size: 3-4

Cost to implement: $50

Learning Goals:

After the lesson, students should be able to:

  1. Calculate launch velocity from location of landing and flight time of water balloon
  2. Resolve the velocity components of an angled launch
  3. Know the relation of the times to top of flight trajectory and time to landing
  4. Determine the location of water balloon landing

Level of Inquiry:

Students should question the possible errors in this lesson (air resistance, angle and distance measurements, consistent launches). They should realize that the target is not exactly on the ground and where the water balloon becomes a projectile and question how to perform the calculations accordingly.

Introduction / Motivation:

The lesson can start out as a mission briefing for a classified operation. Assume the role of a special agent sent from Angry Birds Corporation to inform the agents in training (students) of a plan to exact revenge on a teacher or school administrator.

Present equations of projectile motion and ask students which equations to use in conjunction with their knowledge of the trajectory. If possible, build student excitement by having the target taunt the students of their ability to accomplish the mission.


Lesson Background Concepts for Teachers:

Figure 1: 2-D projectile motion from ground

Figure 2: 2-D projectile motion from a height h off ground

Determine Launch Velocity

Option 1: From Horizontal LaunchOption 2: From Angled Launch at 40 degrees

Time to reach the top of trajectory

Procedure:

  1. Initial Setup
  2. Fill up balloons with same amount of water each

  1. Determine initial launch velocity (choose horizontal and/or angled launch)
  2. IMPORTANT: Pay attention to where the balloon becomes a projectile. It will affect the landing location. You may need to account for the height h as seen in Figure 2.
  3. Option1: Horizontal Launch
  4. Horizontally pull launcher back the length of the string and release water balloon from a height of meters
  5. Measure the horizontal distance that the water balloon travels in meters
  6. Calculate launch velocity in m/s using equations of horizontal/vertical motion
  7. Option 2: Angle Launch
  8. Pull launcher back the length of the string and measure launch angle using protractor
  9. Release launcher and record flight time using stopwatch
  10. Measure in meters

  1. Angle Launch
  2. With the given launch angle , calculate the horizontal and vertical velocity components in m/s
  3. Calculate the horizontal distance the water balloon is expected to travel in meters
  4. Ask teacher to position himself at that distance from launcher. See 2a.
  5. Launch and record whether the water balloon hits the target. Measure the actual horizontal distance in meters
  1. EXTRA CREDIT: Launch at target with horizontal distance known
  2. Answer Question 4 first
  3. Measure horizontal distance of the target from the water balloon launcher in meters
  4. With the calculated initial launch velocity from 2 and measured horizontal distance, calculate the launch angle (from Question 4)
  5. Launch at this angle and measure the horizontal distance traveled in meters

Materials List

Each group will need:

  1. String
  2. Meter stick
  3. Water
  4. Water balloons
  5. Protractor

To share with the entire class:

  1. Water balloon launcher
  2. Funnel with four holes drilled
  3. Latex/surgical tubing, at least 50 ft
  4. Washer
  5. Rope
  6. Anchors

Safety Issues:

  1. Watch for recoil of launcher
  2. Guard balloons

Lesson Closure:

Regroup the class and begin asking the class what gave them difficulties in calculations and execution. Poll the class for areas of possible errors and ask them how that would influence the outcome (overshoot or undershoot). Review the concepts and equations of motion once more.

Assessment:

Pre-Activity Assessment:

Ask them concepts and equations for projectile motion as you fill out Figure 1 or Figure 2 as a class.

Activity Embedded Assessment:

Walk around to groups and ask them which step they are at. Have them voice what they are doing.

Post-Activity Assessment:

Listen to their responses and comments after the lesson, paying attention to their excitement level and ability to analyze their performance in the lesson.

Is this lesson based upon or modified from existing materials? If yes, please specify source(s) and explain how related:

References:

The construction of the water balloon is viewable from the following YouTube video:

Attachments:

  1. Angry Students.doc [Handout for instructor]
  2. Angry Students for Students.doc [Handout for students]
  3. Angry Students.pptx [Highlights and reflections of lesson at Culver City HS]

CA Science Standards addressed: Motion and Forces Standards

  1. Students know how to solve two-dimensional trajectory problems
  2. Students know how to resolve two-dimensional vectors into their components and calculate the magnitude and direction of a vector from its components