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Q9.8: NCERT Physics - Part 2 MECHANICAL PROPERTIES OF FLUIDS 9.8 Solution: A hydraulic automobile lift is designed to lift cars with a…

⚠️ Common Exam Traps & Conceptual Pitfalls

Students often convert the piston area by using $1\text{ cm}=0.01\text{ m}$ directly, forgetting that area units must be squared; the correct conversion is $1\text{ cm}^2=10^{-4}\text{ m}^2$. Using the wrong factor inflates or deflates the pressure by a factor of $10^4$.

A hydraulic automobile lift is designed to lift cars with a maximum mass of 3000 kg. The area of cross-section of the piston carrying the load is 425 cm_. What maximum pressure would the smaller piston have to bear?

Step-by-Step Verified Solution

**Answer:** 6.92×105 Pa6.92 \times 10^5 \text{ Pa} **Step-by-Step Explanation:** Force on large piston: F=mg=3000×9.8=29400F = mg = 3000 \times 9.8 = 29400 N. Area of large piston: A=425A = 425 cm_ =425×10−4=0.0425= 425 \times 10^{-4} = 0.0425 m_. Pressure:
P=FA=294000.0425=6.92×105 PaP = \frac{F}{A} = \frac{29400}{0.0425} = 6.92 \times 10^5 \text{ Pa}
By Pascal's law, this pressure is transmitted to the smaller piston.

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