Question

In a hydraulic jack as shown, mass of the car $W=800\, kg , A_{1}=10\, cm ^{2}, A_{2}=10\, m ^{2}$. The minimum force $F$ required to lift the car is

• A. 1 N
• B. 0.8 N
• C. 8 N
• D. 16 N

Answer 1

Answer: (B)

Pressure in a liquid is divided equally so we can say pressure at both the pistons should be same
$\Rightarrow \frac{F_{1}}{A_{1}}=\frac{F_{2}}{A_{2}}$
Substituting values,
Where,
$F_{1}=F$
$A_{1}=10\, cm ^{2}$
$A_{2}=10\, m ^{2}=10 \times 10^{4} cm ^{2}$
$F_{2}=8000\, N$
$\Rightarrow F=0.8\, N$
$\{\text {Take} g=10\, m / s ^{2}\}$