XIV. The work done by a muscle, a. To determine the 



amount of work done by a single contraction. 



b. To determine the total amount of work 



done by a muscle, c. Reaction 



changes in fatigued muscle. 



/. Appliances. Same as in lesson XIII.; also 50-gramme 

 weight and 20 or 30 gramme weight. 



2. Preparation. Arrange electrical apparatus for a series, 

 of break induction shocks. 



f. Operation, Make and mount a gastrocnemius prepara- 

 tion for indirect stimulation. 



4.. Observations. Upon a slow drum record in close order a 

 series of break contractions. 



a. To determine the amount of work done by a single 



contraction. 



(1) What weight is lifted? 



(2) How high is it raised? 



(3) What is the ratio between the height of the curve 

 traced by the lever and the height through which 

 the weight was raised? 



(4) Let W = work done. 



g = weight lifted. 



h = height of curve traced by lever. 



K constant of the apparatus, in this case 



the ratio between the lever arms. Then 



W=A,'. g. h. 



(5) Express the amount o^f work in ergs. 



b. To determine total work done. 



(5) How many times was the weight lifted before the 

 muscle was fatigued? 

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