Physics of martial arts kicks ·
Center of gravity (center of mass) · Kinetic energy · Potential energy · Velocity · Momentum · Rotational momentum · Inertia (Newton's First Law of Motion) · Acceleration (Newton's Second Law of Motion) ·
Muscle groups of the hip, leg, and feet.
How can you change a kick in martial arts to improve its impact?
· What is the difference between potential and kinetic energy? ·
What factors increase the potential energy of a kick? ·
What do velocity, mass, and momentum have to do with executing a strong and efficient kick? ·
What principal muscle groups are involved in front, side, and back kicks?
Which additional muscles are necessary for a turning kick? ·
Define center of gravity. Describe how it shifts when delivering each type of kick.
Materials and EquipmentTo do this experiment you will need the following materials and equipment·
Karate kick boxing bag (hanging or upright) · Workout room or open space to kick the bag · Assistant to evaluate the kicks · Notebook or paper · Pen or pencil Experimental Procedure
1. Select your favorite front, side, back, and rotational kick for your experiments.
2. Set up your kick bag, and review with your assistant the procedures of the experiments.
3. The assistant will stand to the side of the bag and note how far the bag moves or swings after each kick. They will also reposition the bag to a still, vertical position after each kick.
4. The assistant should give each kick a "power rating" based on how far the bag moves from the vertical position. For example, use a 0–5 scale such as 0 = no movement of the bag; 1 = slight wobble; 2 = slight swing (10–20 degrees) 3 = medium swing (up to 45 degrees); 4 = hard swing (45–90 degrees); 5 = bag moved > 90 degrees (or was knocked over).
5. Warm up a few minutes by practicing each of the four types of kicks you selected for your experiments. 6. Do the four experiments listed below. The first three experiments have two parts, a slow and fast version of each kick.
7. In all kicks, use your best form, and try to keep the height of your kicks and the point where you hit the bag consistent. For slow kicks, concentrate mainly on good, consistent form, and don't worry about speed. For fast kicks, kick your leg as quickly as possible, but try to maintain good form at all times.
8. For each experiment and speed, do ten kicks in a row. Alternate feet after each kick so you don't always use your "favorite" leg throughout an experiment.
9. Record in your notebook the "power ratings" of each 10 kicks as they are done in every experiment. a. Experiment 1: Front kick–Slow and Fast versions b.
Experiment 2: Side kick–Slow and Fast versions c.
Experiment 3: Back kick–Slow and Fast versions d.
Experiment 4: Rotational kick (Any kick that involves a turn before hitting the bag) Analyzing Your Data1. Total the ten "power ratings" from each type of kick. Calculate an average rating for each kick type. 2. Prepare a bar graph showing the average power rating for all kicks.
3. Rank the kicks from highest to lowest according to their average power ratings.
4. Did one type of kick stand out as most powerful, or were all the kicks fairly close in power ratings? Is this what you expected?
5. How did speed influence the power of a kick, if at all?
6. Reviewing the muscle groups in the legs and feet, describe how muscle group or size influences the outcome of a kick.
7. For help with data analysis and setting up tables, see Data Analysis & Graphs.
8. For a guide on how to summarize your results and write conclusions based on your data, see Conclusions. Variations· Does Mass Matter?
Recruit a martial arts friend who is much smaller or larger than you. Ask them to do the same experiments. Compare your results to those of your friend. Are the results what you expected? Why or why not? ·
Do the Math. Research the mathematical equations that describe the force generated during the motion of a kick on a kick bag. Describe mathematically the different levels of energy or power that can be generated from the various kicks you did in your four experiments. Show mathematical examples of how speed, mass, distance from the bag, and rotational momentum may influence the power of a kick. · The Strike Zone. Use a speed bag and repeat these experiments with three different arm strikes instead of kicks. For example, compare front strikes to back strikes, or elbow strikes to hand and forearm hits. Compare these results to results from your first set of experiments with kicks. Explain your findings in terms of mass, velocity, momentum, and inertia.
