Week 3:

Horizontal Acceleration

Laboratory

Warm-up

Review full body warm-up and continue with new material. Emphasize alignment principals especially in relation to the spine’s alignment with gravity’s vertical line of force. Introduce the five basic foot positions of classical ballet and rationale for their development. Introduce lunge positions forward, side and back.

Movement Activities

Explore acceleration on horizontal paths.

a) Begin with a simple fall off balance forward and recover. Sense the action of fall and recovery.

b) Run across the room in lines. Explore starting from simple standing position, feet below hip sockets. Sense the speed of acceleration and the tilt of the body in the process. Repeat and focus on the negative acceleration at the end of the run. Again sense the tilt of the body as you slow down. Tune in especially to the feelings/actions of the feet.

c) Now begin a run from fourth position (one foot directly in front of the other approximately 1.5 feet, turned out from the hip socket. Explore lifting the front foot and falling forward in to acceleration. Sense the difference from the simple standing starting position. What do your arms want to do to increase your acceleration?

d) Try the same movements from fifth position (a narrow base with one foot directly in front of the other, turned out from the hips).

e) Finally try starting from second position (feet apart side to side about 1.5 feet, turned out from the hips) but start moving sideways. How is this different, easier, harder? Explore starting to run backwards. What is different than forward acceleration?

f) In two groups jog quickly in a large circle clockwise, reverse and run counterclockwise. What does your body (torso, arms) want to do? In four groups, two at a time run in the same size circle but as fast as you can. How is your body’s (torso, arms) reaction different? What is the sensation in your feet?

Students achieve horizontal acceleration but have to consciously push against the floor with each step to maintain a circular path.

g) Try running backwards – can you achieve the same speed?

Demonstration

Further instruction in use of calibrated backdrop for use with digital cameras.

Experiments

Make a video of simple run starts and stops in front of the scaled backdrop. Note that due to the distance required, you will likely capture only a start or a stop in any clip (not a whole run and stop). Use variations in starting positions of the feet, body position and arm movement to change the start/stop effectiveness. Discuss how these changes might connect to the physical outcome using physical concepts as clearly as possible.

Simple horizontal run from first position.

Try filming someone running in a circle. Use a vertical marker (pole provided) to measure one point on the perimeter of the circle where the body tilt can be measured. Calculate the velocity of the run and the degree of tilt. Try different velocities. If you have good running shoes you could perhaps do this in the driveway behind the studio or out on the lawn. Two teams may need to work together.

Analysis - Experiential/Aesthetic

Write down in lab notebook your kinesthetic experiences. What did it feel like? Be sure to comment on all underlined prompts either asking a question or asking you to notice kinesthetic sensations.

1) Respond to prompts with a special attention to how different starting positions, body facings etc. affected your results and kinesthetic sensing.

2) Comment in general on the feeling of acceleration and negative acceleration. Based on this reflection how might you improve the rate of your acceleration?

3) Don’t forget to include the experiential/aesthetic component of the experiments that you do.

4) Note any conclusions from the lab experiences today.

Physical Lab Component-Calculation of Velocity/Estimation of Acceleration

Analysis

On the computer do a frame-by-frame video analysis of horizontal position vs. time for at least two different runs that you want to compare. Be sure to indicate your assumptions for the analysis (what part of the subjects body/clothing you use to determine position; where the starting point is on the backdrop etc). Enter your data into Logger Pro and plot position vs. time (remembering the 30 frames/sec capture rate and the scale conversion from screen to room). Now calculate the horizontal velocity by subtracting your position data and dividing by 1/30 second (as discussed in class). You can then plot a velocity vs. time and then estimate the acceleration. How do these results agree (or not) with your predictions for the effects of the body position/arm movement variations that accompany each capture?

Conclusions

After your analysis, make a summary of your results AND your understanding of them. Address what worked well, where there might have been errors in the measurement, and what changes might make the experiments work better next time.