A friendly physics lesson: I recently read and enjoyed the Grail Quest series, and I’m sure you receive plenty of mail with historical nitpicks. Here’s a scientific one. At the end of Heretic, whin Guy is charging Thomas, he is stopped by an arrow. The quality of an object which determines how well it can change another’s velocity in a collision is its momentum. A 0.4kg arrow travelling at 50m/s has a momentum of 20 kg m/s. A 100 kg man in plate running at 5 m/s has a momentum of 500 kg m/s. If the arrow sticks to him, then he’d still be moving at 4.8 m/s after the collision. You can also think about it in terms of conservation of momentum: any ‘kick’ that Guy received would also be received by Thomas in the opposite direction when he launched the arrow. If Thomas is not thrown back when he launches the arrow, Guy won’t be thrown when he receives it. The same applies to gunfire. This doesn’t mean that arrows couldn’t do a great deal of damage to armor and flesh – that’s a result of the arrow’s kinetic energy. Most of the energy a strong archer uses pulling the bowstring back is used to destroy the arrow and the target on impact. Chuck Bean, Physics teacher