Determine the SI base units used for stress. Show your working.
Beam PQ is clamped so that it stays horizontal. A mass $M$ of $500\,\text{g}$ is suspended from end Q and the beam bends slightly, as shown in Fig. 1.1. The length $l$ from the edge of clamp R to end Q is $60.0\,\text{cm}$. The beam width $b$ is $30.0\,\text{mm}$ and the thickness $d$ is $5.00\,\text{mm}$. The beam material has Young modulus $E$. The mass $M$ is then made to oscillate vertically. The oscillation period $T$ is $0.58\,\text{s}$. The period $T$ is given by the expression $T = 2\pi \sqrt{\frac{4Ml^3}{Ebd^3}}$. (i) Determine $E$ in $\text{GPa}$.
Explain the difference between accuracy and precision.
In one experiment, $l$ and $T$ each have the same percentage uncertainty. State and explain which of these two quantities contributes more to the uncertainty in the value of $E$.