(a). Discuss two situations in daily life where we apply the concept of pressure.
(b). A body of density `rho` is dropped gently on the surface of a liquid of density `rho'` `(rho'` being less than `rho`). Show That it will reach the bottom of the liquid after a time `sqrt((2drho)/(g(rho-rho')))`, where g is acceleration due to gravity and d is the depth of the liquid.

Explanation

(a). N/A
(b). If m is the mass of the body, its volume is given by `V=m//rho`
The upthurst due to displaced liquid, `F_(B)=Vrho'g=((m)/(rho))rho'g=mg(rho'//rho)`
The resultant downward force on the body within liquid,
`F=mg-F_(B)=mg-mg(rho'//rho)=mg(1-rho'//rho)`
Acceleration of the body while moving in the liquid.
`a=(F)/(m)=g(1-rho'//rho)`
since the body starts from rest from the surface of liquid.
`d=(1)/(2)at^(2)=(1)/(2)g(1-rho'//rho)t^(2)=(1)/(2)g((rho-rho')/(rho))t^(2)`
or `t=sqrt((2drho)/(g(rho-rho')))`