Question

Find the resistance offered by the nail A.

Answer 1

3.4 × 10³ N.

Explanation

The perpendicular distance between the 400 N force and the fulcrum is $120 \; \text{mm} = 0.120 \; \text{m}$.

What's the perpendicular distance between the friction of the nail and the fulcrum?

Refer to the diagram attached. The perpendicular distance between the nail and the fulcrum is $0.015 \; \cos{20\textdegree{}} = 0.0141 \; \text{m}$.

What's the size of the friction of the nail?

$F_\text{friction} \cdot l_\text{friction}= F_{\text{400} \; \text{N}} \cdot l_{\text{400} \; \text{N}}$

$F_\text{friction} = \dfrac{F_{\text{400} \; \text{N}} \cdot l_{\text{400} \; \text{N}}}{ l_\text{friction}}\\\phantom{F_\text{friction}} = \dfrac{400\times 0.120}{0.0141}\\\phantom{F_\text{friction}} = 3.4\times 10^{3} \; \text{N}$.