The nine ring wraiths want to fly from barad-dur to rivendell. rivendell is directly north of barad-dur. the dark tower reports that the wind is coming from the west at 69 miles per hour. in order to travel in a straight line, the ring wraiths decide to head northwest. at what speed should they fly (omit units)?

Velocity of the ring wraiths relative to the air:

The speed is what we want to find - this is the speed at which the wraiths are flying in the air.

(Note: denotes velocity, while denotes speed)

Velocity of air relative to the ground:

The ring wraiths want their trajectory to be due north, which means their velocity relative to the ground should be

To an observer on the ground, is the speed at which the wraiths would appear to be moving in the air.

The relative velocities satisify

answer: do we write it

step-by-step explanation: