Asked Dec 10, 2019

A high-speed swimmer uses 120,000 � of energy in a half-minute race. Three quarters of the energy is
wasted through heat flow; the rest is dissipated by his hands and legs, by mechanical work.
a. In 30 �, he swims 50 �. Estimate the average force opposing his motion.
b. Describe the changes of form of energy in the swimming.
c. Where and in what form is the energy that had been released when he has finished the


Expert Answer

Step 1

a) the one fourth of energy used to oppose the motion which is nothing but 120,000*(1/4) is equal to 30000 J.

the energy is same as the work done.

the expression for the work done is, 


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W = Fd

Step 2

substitute the known values in the above equation to calculate F


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30000 J = F(50m) F = 600 N

Step 3


the total energy converted to mechanical ene...

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