Why are some fasteners double or triple threaded?

Foreshadowing. the prologue states that this is the story of "star-crossed lovers." there are four strong foreshadowings of evil in act 1. identify at least two foreshadowings and explain their purpose.

We put a force of 50n on an object and the acceleration is 100 m/s². what is the mass of the object?

On a day when the barometer reads 75.23 cm, a reaction vessel holds 250 ml of ideal gas at 20 celsius. an oil manometer ( ρ= 810 kg/m^3) reads the pressure in the vessel to be 41 cm of oil and below atmospheric pressure. what volume will the gas occupy under s.t.p.?