Fundamentals of Biomechanics

L-16 FUNDAMENTALS OF BIOMECHANICS
LAB ACTIVITY 6B
IMPULSE–MOMENTUM: FORCE–TIME PRINCIPLE
The timing of force application to objects affects the stress and motion created. Newton's second law
applied to forces acting over time is the impulse–momentum relationship. The change in momentum
of an object is equal to the impulse of the resultant force. This activity will allow you to experience
some interesting real-life examples of the impulse–momentum relationship. The purpose of this lab is
to improve your understanding of changing the motion of an object (specifically, it's momentum) by
applying force over a period of time. In some ways body tissues are similar to water balloons in that
too much force can create stresses and strains that lead to injury. It is important for teachers/coaches
to understand how movement technique affects the impulse and peak force that can be applied to an
object. This lab is modified from a lab proposed by McGinnis and Abendroth-Smith (1991).
Chapter 6 herein: “Linear Kinetics”
BACKGROUND READING
McGinnis, P., & Abendroth-Smith, J. (1991). Impulse, momentum, and water balloons. In J. Wilkerson,
E. Kreighbaum, & C. Tant, (Eds.), Teaching kinesiology and biomechanics in sports (pp. 135–138).
Ames: Iowa State University.
Knudson, D. (2001c). Accuracy of predicted peak forces during the power drop exercise. In J. R.
Blackwell (Ed.) Proceedings of oral sessions: XIX international symposium on biomechanics in sports
(pp. 135–138). San Francisco: University of San Francisco.
TASKS
1. Estimate how far you can throw a softball-sized water balloon. _____
2. Estimate the maximum distance you could catch a similar water balloon. ____
3. Fill several water balloons to approximately softball size (7–10 cm in diameter).
4. Measure the maximal distance you can throw the water balloon. _____
5. Measure the maximal distance you and a partner can throw and catch a water balloon. _____
6. Answer the questions.
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