Q. A piston of cross-section area $100\ cm^{2}$ is used in a hydraulic press to exert a force of $10^{7}$ dynes on the water. The cross-sectional area of the other piston which supports an object having a mass $2000\ kg$. is
A) $100\ cm^{2}$
B) $10^{9}\ cm^{2}$
C) $2 \times 10^{4}\ cm^{2}$
D) $2 \times 10^{10}\ cm^{2}$
Explanation
(c) $P_{1} = P_{2} \Rightarrow \frac{F_{1}}{A_{1}} = \frac{F_{2}}{A_{2}} \Rightarrow \frac{10^{7}}{10^{2}} = \frac{2000 \times 10^{3} \times 10^{3}}{A_{2}}$
$\therefore A_{2} = 2 \times 10^{4}cm^{2}\ \ \ \ (g = 980 \approx 10^{3}cm/s^{2})$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.