Human heart pumps #50cm^3# blood in every pump against 10 cm hg pressure. If heart pumps 72 times a minute then what is the power of heart?

1 Answer
A08
Jun 21, 2017

#0.8W#

Explanation:

We know that
#"Work" = "Force" xx "Distance" #
#=>"Work" = ("Pressure" xx "Area") xx "Distance"#
Rearranging we get
#"Work" = "Pressure" xx "Volume"# ......(1)

We also know that power is rate of doing work.
#:."Power" = "Work"/"Time"#

Using equation (1) we get
#"Power" = ("Pressure" xx "Volume")/"Time"#

#=>"Power" = (hrhog xx "Volume")/t#
where #h# is height of mercury, #rho=13593kgm^-3# is density of mercury, #g# is acceleration due to gravity #=9.81ms^-2#

Inserting various values in SI units we get
#"Power" = (0.1xx13596xx9.81 xx (50/100^3xx72))/60#
#"Power" = 0.8W#

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