Question

The area of cross section of the wider tube shown in figure is 900 ${cm}^2$. If the boy standing on the piston weighs 45 kg, the difference in the levels of water in the two tubes.

• A. 50 cm
• B. 25cm
• C. 75 cm
• D. 100 cm

Answer 1

The correct option is A 50 cm

R.E.F image

$A_1=900c{m}^2$

$F_1=45g$ newton

difference of water level = l

pressure at right end P =$\frac{F_1}{A_1}=\frac{45g}{.09m^2}$

so pressure in the right arm for the difference l scaled maintain the pressure

otherwise liquid will have either towards right or left.

so $\frac{45\times 10}{.09}=pgh=\frac{1000kg}{m^3}\times 10\times l$

$\Rightarrow l=\frac{45}{.09\times 1000}m=\frac{4500}{90}cm=50cm$