Penny Motion

In this activity, students explore the horizontal and vertical components of horizontal motion.

Activity Details

Grade Level: High School

Age:15-18

Content:Velocity, Acceleration, Trajectory, Physics

Objectives:

• Children represent motion based on calculations of acceleration or velocity using framerate control in SAM Animation.
• Students explore differences in position betwee discrete time steps (defined by the framerate) for constant velocity versus accelerated motion.
• Students explore the application of equations of motion, leading to a deeper understanding of the numbers and the model each equation predicts.

Activity Overview

In the Classroom:

• Students should begin by chosing a framerate for their movie. An FPS of 10 means that each picture will be 0.1 seconds apart, thus a 5 second movie would have 50 frames.
• Select initial velocities, both horizontal and vertical (recommended values are 3 - 5 m/s).
• Set a scale - students will be animating a penny, so they must choose how to represent meters on a piece of graph paper.
• Estimate the number of calculations needed based on the framerate (e.g., a frame rate of 5 fps in a 4 second movie requires 20 frames, hence 20 calculations).
• Set up the calculation table (worksheet template included): t, x, y, xs, xy (where xs and xy are the scaled measurements to be used in the animation).
• Using the appropriate equations of motion, fill in the table for both constant horizontal velocity and for vertical accelerated motion.
• Animate constant horizontal velocity by placing the penny at the appropriate point for each time step. Take a picture, move it to the next position, take a picture, etc.
• Do the same for the vertical motion (this should look as though you have thrown a ball up into the air).
• Plot the xs positions from the horizontal motion with the ys positions from the vertical motion - this will create a parabolic trajectory.
• Test your model by pressing the play button!

Tips:

• Microsoft Excel can help the students manage their calculations
• If students struggle with scaling, have them create rulers that are to scale. These measuring devices read meters but are scaled to milimeters or centimeters, depending. These tools can help the students make sense of the numbers in the calculation table and in the animation.

Questions for students:

Extensions:

• Applying these concepts to real-world settings (soccer, basketball, skiing, etc.) can offer another angle for the students to approach the equations of motion.

Comments:

One way to help students with scale is to provide them with several scaled rulers -- 1m = 1cm, 1m = 2cm, 1m = 10cm, etc. Their challenge is to pick the right ruler to use based on some reference within their movie. Say, for instance, a lego character is being used in the movie and you define the real height of the lego character as 1.5 meters. The students then pick the appropriate scaled ruler and use that to measure out the points from their calculations.