Hands-on Activity Magical Motion

Learning Objectives

After this activity, students should be able to:

• Describe displacement, velocity and acceleration.
• Describe gravity.
• Describe projectile motion.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

NGSS: Next Generation Science Standards - Science

Common Core State Standards - Math

International Technology and Engineering Educators Association - Technology

State Standards

Materials List

To share with the entire class:

• DVDs of October Sky and Harry Potter and the Sorcerer's Stone (borrow from your school or public library so you can show students specific portions; if not available, describe the scenes, since most students are familiar with the movies and will be able to recall the scenes and describe them more fully to other classmates)
• DVD player and screen/monitor, to show the class the movie clips
• 3 stopwatches

Pre-Req Knowledge

Some familiarity with displacement, velocity and acceleration.

Introduction/Motivation

(Begin by showing a video clip from October Sky. In the clip, the main character, Homer Hickam, calculates the trajectory of a homemade rocket in front of his science class.)

What happened in that video clip? (Expect students to say that Homer calculated the rocket's trajectory.) How might an engineer's knowledge of how something moves help people? (Expect student answers to vary greatly. Example answers: An engineer may use his or her knowledge of force and motion to make sure that airplanes land in the right places, to design better cars, to design earthquake-resistant structures.)

Do you think it is difficult to calculate the projected motion of an object? (Expect students to say yes, beeause the movie made it look difficult.) It is actually not as difficult as it looks. Today in class we are going to do the exact same calculations shown in October Sky.

Procedure

Background

In this activity, students make projectile motion calculations using information they gather from watching and measuring a Harry Potter and the Sorcerer's Stone movie clip. They use the equations of motion introduced in the associated lesson. Ultimately, students determine that the amount of time the ball traveled in the video clip was unreasonable and discuss why.

Expect students who have had experience with the equations of motion to be able to complete this activity in small groups or individually. Otherwise, conduct the activity as a class.

With the Students

1. Show a video clip from Harry Potter and the Sorcerer's Stone. In the clip, Hogwarts students are introduced to flying on broomsticks. Harry confronts Malfoy to try to get Neville's remembrall back. Malfoy throws the remembrall and Harry races after it, making a spectacular catch.
2. Ask students to describe the motion of the remembrall. Draw Figure 1 on the board.

   

3. Give three students stopwatches and ask them to time how long the remembrall was in the air while watching the movie clip again. Average the times the three students found using their stopwatches. Expect them to record times close to 11 seconds. For the remainder of the activity, we assume 11 seconds is the airborne time.
4. Direct students to look at the diagram on the board. Point out that with the arch-type projectile motion on the board, the ball was moving both from left to right and up then down. Tell students that for this activity we will ignore the left to right motion and only be considering the up and down motion. Ask students to make an assumption about the amount of time it took for the ball to go up and the amount of time it took for the ball to go down. Expect students to suggest splitting the total amount of time in half. Indicate those amounts of time on the classroom board diagram (as shown in Figure 2).

   

5. Ask: What is the primary force acting on the remembrall as it moves down? (The correct answer is gravity.) What is the acceleration of gravity? (The acceleration of gravity is 9.81 m/s².)
6. Ask students to determine the downward velocity of remembrall when Harry catches it. Since the initial velocity at the top of the arc is 0, the correct equation of motion is:

   

   This yields a velocity of 54.0 m/s.
7. Now ask students to calculate the distance the remembrall fell from the time it was at the top of the arc until Harry caught it. Since the initial velocity at the top of the arc is 0, the correct equation of motion is:

   

   This yields a distance of 148.5 meters.
8. Discuss with students the reasonableness of these answers. Is it reasonable that the remembrall fell 148.5 meters? Explain why or why not. Point out that 148.5 is about the length of 1.5 football fields! Is this distance reasonable? Does it make sense? Expect students to come to the conclusion that it is unreasonable that the ball fell that far because Malfoy could not have thrown it that high. So, what caused this unreasonableness? The answer is that the 11 seconds measured in the movie clip is unreasonable. The movie makers likely stretched / exaggerated the amount of time the remembrall was in the air to create a feeling of more suspense in the movie.
9. Conclude by assigning students to write descriptions of how engineers use their understanding force and motion, as described in the Assessment section.

Vocabulary/Definitions

acceleration: The rate of change of velocity with respect to time.

displacement: The difference between the first position of an object and any later position.

velocity: The rate of change of position with respect to time.

Assessment

Pre-Activity Assessment

Class Discussion: Discuss how engineers use their knowledge of how things move to create devices, equipment, products and structures that benefit people.

Activity Embedded Assessment

Class Discussion: Describe the motion of the remembrall.

Post-Activity Assessment

Writing: Assign students to write descriptions about how engineers might use their understanding of force and motion. Possible examples: An engineer could use his or her knowledge of force and motion to make sure that airplanes land in the right places, to design improved vehicles, to design earthquake-resistant structures, to design a construction crane and its controls so that it accurately picks up and moves extremely heavy loads, to design video players so they precisely and reliably load/unload and play video tapes for us, etc.

Investigating Questions

• What happened in the video clip from October Sky?
• How might an engineer's knowledge of how something moves help our society?
• Do you think it is difficult to calculate the projected motion of an object?
• What happened in the video clip from Harry Potter and the Sorcerer's Stone?
• How much time was the remembrall in the air?
• Describe the motion of the remembrall.
• How much time do you think the remembrall spent going up? Going down?
• What forces were acting on the remembrall?
• What is the acceleration of gravity?
• What was the downward velocity of the remembrall when Harry caught it?
• How far did the remembrall fall from the top of the arc until Harry caught it?
• Was the distance that the remembrall fell reasonable? Why or why not?
• How might an engineer use his or her knowledge of force and motion?

Activity Extensions

Show some additional Harry Potter video clips that show projectile motion. Conduct the activity again, this time by timing how long the various quidditch balls were airborne.

Activity Scaling

• Expect more advanced students who have had experience with the equations of motion to be able to complete this activity in small groups or individually.
• For younger students who have no experience using the equations of motion, conduct this activity as a class.

Additional Multimedia Support

Borrow from your school or public library DVDs of October Sky and Harry Potter and the Sorcerer's Stone movies, so you can show students the clips. If not available, describe the scenes, since most students are familiar with the movies and will be able to recall the scenes and describe them more fully to other classmates.

References

Copyright

Contributors

Supporting Program

Acknowledgements

This digital library content was developed by the University of Houston's College of Engineering under National Science Foundation GK-12 grant number DGE 0840889. However, these contents do not necessarily represent the policies of the NSF and you should not assume endorsement by the federal government.