Magical Motion
Do you remember the scene when Harry Potter (on a broom) catches the remembrall that Malfoy throws (on a broom)?Copyright 2011 Rachel Howser, GK-12 Program, University of Houston
Students watch video clips from the October Sky and Harry Potter and the Sorcerer's Stone movies to see examples of projectile motion. Then they explore the relationships between displacement, velocity and acceleration, and calculate simple projectile motion. The objective of this activity is to articulate concepts related to force and motion through direct immersive interaction based on "The Science Behind Harry Potter" theme. Students' interest is piqued by the use of popular culture in the classroom.
Many types of engineering disciplines rely upon the concepts of force and motion. Mechanical engineers use their knowledge of force and motion to design engines that transport goods and people, machines and tools such as vacuum cleaners and factory assembly equipment that make our ways of life possible, as well as many other types of devices and products. Structural engineers apply their understanding of force and motion to design structures that can withstand normal forces (such as traffic or wind loads) and atypical forces (such as earthquakes, monsoons and hurricanes) so that we are safe during everyday activities and disasters. Aerospace engineers must understand forces and physical properties as they design aircraft, rockets and spacecraft, including predicting projectile motion.
After this activity, students should be able to:
- Describe displacement, velocity and acceleration.
- Describe gravity.
- Describe projectile motion.
- CCSS.Math.Content.6.EE.A.2c Evaluate expressions at specific values of their variables. Include expressions that arise from formulas used in real-world problems. Perform arithmetic operations, including those involving whole-number exponents, in the conventional order when there are no parentheses to specify a particular order (Order of Operations).
Grade 6
Do you agree with this alignment? - CCSS.Math.Content.HSA-REI.B.3 Solve linear equations and inequalities in one variable, including equations with coefficients represented by letters.
Grades 9-12
Do you agree with this alignment?
- Students will develop an understanding of the role of society in the development and use of technology.
Grades K-12
Do you agree with this alignment?
- MS-PS2-2 Plan an investigation to provide evidence that the change in an object's motion depends on the sum of the forces on the object and the mass of the object.
Grades 6-8
This resource focuses on the following Three Dimensional Learning aspects of NGSS:
Science & Engineering Practices- Plan an investigation individually and collaboratively, and in the design: identify independent and dependent variables and controls, what tools are needed to do the gathering, how measurements will be recorded, and how many data are needed to support a claim.Do you agree with this alignment?
- Science knowledge is based upon logical and conceptual connections between evidence and explanations.Do you agree with this alignment?
Disciplinary Core Ideas- The motion of an object is determined by the sum of the forces acting on it; if the total force on the object is not zero, its motion will change. The greater the mass of the object, the greater the force needed to achieve the same change in motion. For any given object, a larger force causes a larger change in motion.Do you agree with this alignment?
- All positions of objects and the directions of forces and motions must be described in an arbitrarily chosen reference frame and arbitrarily chosen units of size. In order to share information with other people, these choices must also be shared.Do you agree with this alignment?
Crosscutting Concepts- Explanations of stability and change in natural or designed systems can be constructed by examining the changes over time and forces at different scales.Do you agree with this alignment?
Do you agree with this alignment? - Plan an investigation individually and collaboratively, and in the design: identify independent and dependent variables and controls, what tools are needed to do the gathering, how measurements will be recorded, and how many data are needed to support a claim.
- compare and contrast potential and kinetic energy;
Grade 6
Do you agree with this alignment? - identify and describe the changes in position, direction, and speed of an object when acted upon by unbalanced forces;
Grade 6
Do you agree with this alignment? - calculate average speed using distance and time measurements;
Grade 6
Do you agree with this alignment? - measure and graph changes in motion; and
Grade 6
Do you agree with this alignment? - investigate how inclined planes and pulleys can be used to change the amount of force to move an object.
Grade 6
Do you agree with this alignment?
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
Some familiarity with displacement, velocity and acceleration.
(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.
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
- 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.
- Ask students to describe the motion of the remembrall. Draw Figure 1 on the board.Figure 1. Projectile motion of the remembrall, a device from the Harry Potter wizardry world.Copyright 2011 Rachel Howser, GK-12 Program, University of Houston
- 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.
- 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).
Projectile motion of the remembrall with times indicated.Copyright 2011 Rachel Howser, GK-12 Program, University of Houston - 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.)
- 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. - 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. - 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.
- Conclude by assigning students to write descriptions of how engineers use their understanding force and motion, as described in the Assessment section.
- 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.
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.
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.
- 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.
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.
Dictionary .com. Lexico Publishing Group, LLC. Accessed March 25, 2011. http://www.dictionary.com
Contributors
Rachel Howser; Christine Hawthorne
Supporting Program
National Science Foundation GK-12 and Research Experience for Teachers (RET) Programs, University of Houston
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.
Copyright
2013 by Regents of the University of Colorado; original © 2011 University of Houston