UMass Amherst KIN 430 - BiomechLabH (2 pages)

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BiomechLabH



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BiomechLabH

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Pages:
2
School:
University of Massachusetts Amherst
Course:
Kin 430 - Biomechanics
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Biomechanics Laboratory H Work and Power INTRODUCTION Mechanical work and power are two measures that are of interest to many biomechanists Depending on the situation the focus may be on work power or both Work is equal to the product of force and displacement work J force N displacement m If the time it takes for a force to produce a certain displacement is known then the rate at which work is done can be determined this is known as power Power can alternatively be computed by multiplying force and velocity power J s or W work J force N velocity m s time s Mechanical power is especially useful in evaluating physical performance as it is an indicator of the intensity of a task Computations of work and power underlie many tests of human anaerobic performance capacity Some of these tests involve having subjects pedal a bicycle ergometer as fast as possible jump for maximum height or sprint up a flight of stairs This last type of task will be the focus of this laboratory When climbing a flight of stairs quickly or slowly the average force exerted against the steps is equal to body weight needed to overcome the gravitational force and the displacement of interest is the vertical displacement of the staircase So all of the mechanical work is done in the vertical direction There is no force resisting motion in the forward direction so there will be no horizontal work done even though there is a horizontal displacement METHODS Each person in the lab section will sprint up a flight of stairs as quickly as possible This will be done three separate times One person will stand at the top of the stairs with a stopwatch This person will start the stopwatch and simultaneously issue a ready set go command The stopwatch will be stopped when the sprinter s foot touches the top step All sprints will begin from a dead stop right at the bottom of the stairs When sprinting up the stairs go two stairs at a time and be careful Worksheet use your own data Name Subject Weight N Vertical displacement m number of steps height per step Times trial 1 s trial 2 s trial 3 s Compute the mechanical work and power for each trial and report all of the relevant data in the table below Trial Time s Displacement m Force N Work J Power W 1 2 3 average Lab Report Prepare a brief lab report that contains the results you obtained and answers the questions listed below You will submit the lab report through Turnitin on the course Moodle site 1 Do the mechanical work and power values vary from trial to trial Explain why they do or do not 2 Do you think the results of this test are a good indication of your maximal anaerobic capacity i e your maximal power output Explain why or why not 3 Is there anything about the test that you feel may have limited your actual performance and or your computed power values If so what are these factors 4 Different tests of anaerobic performance can give very different results for peak power The following are the peak power output values obtained for one healthy young adult female for three different tests vertical jump 2798 W bike sprint 622 W stair sprint 1033 W Why is there so much variation among the tests if they all are supposed to represent the peak power output for this one person


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