Question

In a car lift, compressed air exerts a force $F$, on a small piston having a radius of $5.0 cm .$ This pressure is transmitted to a second piston of radius $15 cm$. If the mass of the car to be lifted is $1350 kg$, calculate $F$.

• A. $1 \times 10^{3} N$
• B. $1.5 \times 10^{3} N$
• C. $2 \times 10^{3} N$
• D. $2.5 \times 10^{3} N$

Answer 1

Answer: (B)

Since pressure is transmitted undiminished throughout the fluid,
$F_{1}=A_{1}\left(\frac{F_{2}}{A_{2}}\right)$
$=\frac{\pi\left(5 \times 10^{-2} m \right)^{2} \times\left(1350 kg \times 9.8 ms ^{-2}\right)}{\pi\left(15 \times 10^{-2} m \right)^{2}}$
$=1470 N =15 \times 10^{3} N$