To solve this problem, we need to understand how a hydraulic lift works. A hydraulic lift multiplies the force applied using Pascal's principle, which states that pressure applied to a confined fluid is transmitted undiminished in all directions throughout the fluid, regardless of the area over which it was applied.
Given in the problem:
The force applied at the effort arm is balanced by the load at the load arm through the hydraulic lift, which can be expressed by the formula for hydraulic systems:
F_{\text{effort}} \cdot A_{\text{effort}} = F_{\text{load}} \cdot A_{\text{load}}
where:
Assuming both pistons have circular cross-sections, we can use the formula for the area of a circle \( A = \frac{\pi d^2}{4} \). Therefore,
A_{\text{effort}} = \frac{\pi (d_{\text{effort}})^2}{4}
A_{\text{load}} = \frac{\pi (d_{\text{load}})^2}{4}
Substitute \( A_{\text{effort}} \) and \( A_{\text{load}} \) into the original formula, we get:
F_{\text{effort}} \cdot \frac{\pi (d_{\text{effort}})^2}{4} = 10 \cdot \frac{\pi (d_{\text{load}})^2}{4}
By cancelling the common terms and rearranging for \( F_{\text{effort}} \), we have:
F_{\text{effort}} = 10 \cdot \left(\frac{d_{\text{load}}}{d_{\text{effort}}}\right)^2
Substitute the given values:
F_{\text{effort}} = 10 \cdot \left(\frac{1.4}{14}\right)^2
Calculate the above expression:
F_{\text{effort}} = 10 \cdot \left(\frac{1}{10}\right)^2
F_{\text{effort}} = 10 \cdot \frac{1}{100}
F_{\text{effort}} = 1000 \, \text{N}
Thus, the force \( F \) needed to balance the hydraulic system is 1000 N, which is the correct answer.