A boy can reduce the pressure in his lungs to 750 mm of mercury. Using a straw he can drink water from a glass upto the maximum depth of (atmospheric pressure = 760 mm of mercury, density of mercury `= 13.6 gcm^(-3)` )

Options

A. `13.6 cm`
B. `9.8 cm`
C. 10 cm
D. 76 cm

Answer

A

Explanation

By hydrostatic pressure
`h rho g = h _(w). g `
`h _(w) = ( h.rho)/(rho _(w))`
`= (10 xx 10 ^(-3) xx 13.6 xx 10 ^(3))/( 1 xx 10 ^(3))`
where `h = ( 760 xx 10 ^(-3) - 750 xx 10 ^(-3) ) m`
`h = 10 xx 10 ^(-3) m`
`rho 13.6 xx 10 ^(-3) kg // m ^(3)`
`rho _(w) xx = 1 xx 10 ^(3) kg // m ^(3)`
`= 136.0 xx 10 ^(-3)`
`= 13.6 xx 10 ^(-2) m`
`=13.6 cm`