The textbook states: “the earliest known printed text, the Diamond Sutra (a Buddhist scripture), was printed in China in 868 A.D.” It was created using block printing — a technique where individual pages are carved into wooden blocks and pressed onto paper. This text predates Gutenberg's press by nearly 600 years. The Diamond Sutra is a famous Mahayana Buddhist scripture, and the printed copy (now held in the British Library) is remarkable for its technical quality, indicating the technique had been refined over time before this particular copy was made. Note the other important dates: paper milling in Baghdad began as early as 794 AD; Bi Sheng invented movable type in 1041 AD; Gutenberg developed the European printing press in the 1440s; and the first printing press in Muslim territory (Andalusia) operated in the 1480s.

Time of flight $= \dfrac{2v_0}{g}$ (time for vertical displacement to return to zero).

Horizontal range $= u_0 \times \dfrac{2v_0}{g} = \mathbf{\dfrac{2u_0 v_0}{g}}$

Overlap occurs when $n_1 \lambda_1 = n_2 \lambda_2$.

$n_1(650) = n_2(520) \implies \frac{n_1}{n_2} = \frac{520}{650} = \frac{4}{5}$.

Distance $y = \frac{n_1 \lambda_1 D}{d} = \frac{4 \times 650 \times 10^{-9} \times 1.5}{0.5 \times 10^{-3}} = 7.8 \times 10^{-3} \text{ m} = 7.8 \text{ mm}$.

Change in velocity: $\Delta\vec{v} = 40\hat{j} - 30\hat{i}$

$|\Delta v| = \sqrt{30^2 + 40^2} = \sqrt{900+1600} = \sqrt{2500} = 50\text{ m/s}$

Average acceleration $= \dfrac{50}{10} = \mathbf{5\text{ m/s}^2}$

John Locke's 'Two Treatises of Government' laid the groundwork for modern liberal democracy.