Question

A nail is driven into a wooden board by using a hammer. The impact of the hammer on the head of nail produces a thrust of $25N$. If the area of the head is $0.5m{m}^2$ and of the tip is $0.1m{m}^2$, find the pressures on the head and on the tip of the nail.

• A. $5\times {10}^{7}Pa;2.5\times {10}^{8}Pa$
• B. $2.5\times {10}^{7}Pa;5.5\times {10}^{8}Pa$
• C. $3.5\times {10}^{7}Pa;2.5\times {10}^{8}Pa$
• D. $5\times {10}^{7}Pa;3.5\times {10}^{8}Pa$

Answer 1

The correct option is A $5\times {10}^{7}Pa;2.5\times {10}^{8}Pa$

$P=\frac{F}{A}$

$1m=1000mm$
pressure on head : $P=\frac{25}{0.5\times {10}^{-6}}=\frac{25}{5\times {10}^{-7}}=5\times {10}^{7}Pa$

pressure on tip : $P=\frac{25}{0.1\times {10}^{-6}}=\frac{25}{1\times {10}^{-7}}=2.5\times {10}^{8}Pa$