# PHYS ED: Biomechanics Labs

A few examples of Biomechanics Labs I’ve used within my year 10 Sports Science Class.

Velocity vs Acceleration

Students to run a 100m race. A timer is to stand at each 10m interval and record the time taken from the firing of the pistol until the runner passes his/her marker. Record your results in a table (time, interval time, speed). Using the acceleration formula record your results in a table (final velocity, initial velocity, time, acceleration). Discuss:

• The difference between speed and acceleration
• At what interval did you record your greatest speed? Give reasons for this
• Discuss differences that you recorded in the acceleration.  When is acceleration the greatest?

Application of Forces

A. Place a basketball and a medicine ball on the court and push each as hard as you can. Discuss:

• Which ball is harder to move? Explain your answer with reference to mass and inertia.
• Push the balls as hard as you can again and observe them moving away. Which ball had the most acceleration and why?
• Imagine you were to drop the basketball and medicine ball into a sand pit. which object would leave the greater impression? Explain your answer with reference to Momentum

B. Set up a baseball diamond. A runner steps up to home plate and on the whistle runs as fast as they can around the three bases and back to home. Timer records how long it takes for the runner to complete one lap. Run the bases under the following conditions: Must perform a sharp 90 degree turn at each base > Must ‘round’ the bases with a circle or arc type approach. Discuss:

• Why do baseball players prefer to ‘round’ first base in a circle/arc rather than perform a 90 degree turn at each base? Explain your answer with reference to inertia.

C. Complete a broad jump under the following conditions: Standing > 3m run up (use markers) > 6m run up (use markers). Discuss:

• Which jump was the longest? Explain why you think this was the case based on the principle of impulse.

Force Summation

A. Perform a Standing Broad Jump under the following conditions: One leg no arms > two legs no arms > legs and arms. Have three attempts at each jump.  Measure the distance of each jump in meters.

B. Work in pairs. One of the pair throw the tennis ball while the other measures distance and retrieves the ball. Throw the tennis ball from the positions described below.

• Sitting legs crossed, using only your wrist to throw
• Sitting with legs crossed, using wrist and elbow to throw
• Kneeling, using shoulder, elbow and wrist to throw
• Standing with feet together using trunk, shoulder, elbow and wrist to throw
• Standing, then stepping forward with one leg and using trunk, shoulders, elbow and wrist to throw

C. Throw the tennis ball at the target under the below conditions. Have five attempts under each condition and record how many times you hit the target in the table below (ie. out of 5).

Discuss:

• What type of force summation is used for a?
• What type of force summation is used for b?
• Which jump was the longest and why?
• Which throw was the furthest and why?
• In c, how does stepping forward increase the accuracy of performance?
• In c, how does the follow through improve accuracy?

Absorption of Forces

A. Perform two varieties of the vertical jumps on a hard surface. The two jumps you are to perform are: One about 5cm off the ground > The second to the maximum height possible. For each jump observe the amount of knee flexion on landing. Explain your observations by comparing the softer surface results to the hard surface results. Explain your observations with reference to force absorption.

B. In pairs, throw an egg underarm to each other over a distance of about 1 metre. Gradually increase (ie. step back 1m after each throw) the distance of each consecutive throw until the egg breaks. What did you notice about the action of your hands as you received the egg? Did this change as the distance increased?

References:

• Physical Education Studies 1A-1B by Regina Gaujers
• Live it Up, Physical Education (VCE Physical Education Units)