Question

In the previous question, at the mouth of the tap the area of cross-section is 2.5 $c{m}^2$ and the speed of water is 3 m/s. The area of cross-section of water column 80cm below the tap is

• A. 2 $c{m}^2$
• B. 1.5 $c{m}^2$
• C. 1 $c{m}^2$
• D. 0.5 $c{m}^2$

Answer 1

The correct option is B 1.5 $c{m}^2$

Using the equation $v^2=u^2+2as$ we get $v^2=3^2+2g\times 0.8$
This gives us the velocity v as $5m/s$
Thus using the continuity equation $A_1{v}_1=A_2{v}_2$ we get
$3\times 2.5=5\times x$
or
$x=1.5c{m}^2$