Exercise 2: sample answer

A seconds pendulum is roughly a metre long (check), and with a long pendulum the weights and the swinging rod need a tall case to hang and move freely. The anchor escapement also encourages a long, narrow swing, which favours a long pendulum.

On a ship, the deck pitches and rolls, so the pendulum's swing is disturbed, and it no longer keeps a steady rhythm. Changes in gravity and direction on a moving platform make a pendulum an unreliable timekeeper at sea, which is why navigators needed a different kind of clock (Chapter 6).